®
IBM Software Group
Enterprise COBOL Education Using Rational Developer for System Z
Module 3 – Basic COBOL Statements
Jon Sayles, IBM Software Group, Rational EcoSystems Team
© 2006 IBM Corporation
IBM Trademarks and Copyrights
 © Copyright IBM Corporation 2007,2008, 2009. All rights reserved.
 The information contained in these materials is provided for informational purposes
only, and is provided AS IS without warranty of any kind, express or implied. IBM
shall not be responsible for any damages arising out of the use of, or otherwise
related to, these materials. Nothing contained in these materials is intended to, nor
shall have the effect of, creating any warranties or representations from IBM or its
suppliers or licensors, or altering the terms and conditions of the applicable license
agreement governing the use of IBM software. References in these materials to IBM
products, programs, or services do not imply that they will be available in all countries
in which IBM operates.
 This information is based on current IBM product plans and strategy, which are
subject to change by IBM without notice. Product release dates and/or capabilities
referenced in these materials may change at any time at IBM’s sole discretion based
on market opportunities or other factors, and are not intended to be a commitment to
future product or feature availability in any way.
 IBM, the IBM logo, the on-demand business logo, Rational, the Rational logo, and
other IBM Rational products and services are trademarks or registered trademarks of
the International Business Machines Corporation, in the United States, other
countries or both. Other company, product, or service names may be trademarks or
service marks of others.
2
Course Contributing Authors

Thanks to the following individuals, for assisting with this course:





David Myers/IBM
Ka Yin Lam/IBM
Don Higgins/Automated Software Tools Corporation
Steve Wilcenski/Sabre Systems, Inc.
Mike Wrzinski/Sentry Insurance
3
Course Description
 Course Name: COBOL Foundation Training - with RDz
 Course Description: Learn the COBOL language, RDz and learn z/OS terms, concepts and development skills in
this course.
 Pre-requisites: Some experience in a 3rd or 4th Generation Language is expected. SQL is also recommended.
 Course Length: 10 days
 Topics (Agenda)














Getting Started - installing and configuring RDz - and the course materials, and using Eclipse to edit COBOL
COBOL General Language Rules
Basic COBOL Statements
Advanced record and table handling
Debugging Programs - Note: Deep dive on using RDz for common COBOL programming errors (001, 0C4, 0C7, infinite loops, fall-thru, etc.)
Input/Output and Report Writing Patterns
COBOL Subprograms and the Linkage Section
Structured Programming Concepts, professional COBOL development practices and Coding Patterns
Advanced Character Manipulation, COBOL Intrinsic Functions, Date and Time coding patterns, and Language Environment calls
OS/390 Concepts and JCL - Compile/Link & Run Procs on the mainframe
Indexed file Coding Patterns
Sort/Merge, Sequential File Match/Merge and Master File Update Coding Patterns
Accessing DB2 Data and DB2 Stored Procedures
COBOL in the Real World:
– CICS - lecture only
– IMS (DL/I and TM) - ditto
– Batch processing - ditto
– Java calling COBOL
– COBOL and XML Statements
– SOA and COBOL - creating and calling Web Services
– Web 2.0 using Rich UI
4
Course Details
 Audience
 This course is designed for application developers who have programmed in
some language before, and who wish to learn COBOL.
 Prerequisites
 This course assumes that the student has the basic knowledge of IS
technologies, data processing, software and have programmed for at least
two or more years in a language such as: Java, VB, RPG, PL/1, Pascal, or
some 4th Generation Language or tool.
 Knowledge of SQL (Structured Query Language) for database access is
assumed as well.
 Basic PC and mouse-driven development skills is also assumed.
 Finally, it is assumed that you have been following along in this course, and
have successfully completed the learning modules in sequence.
 Or have the equivalent COBOL background obtained through some other form of
COBOL study or on-the-job work.
5
Unit
COBOL General Language
Rules
Topics:
 Assignment Statements and Internal Data
Representation
 Math Operations
 Conditional Logic
 Transfer of control
 COBOL Looping Constructs
 Sequential File Processing Patterns
 Java and .NET Equivalents
6
Topic objectives
After completing this topic, you should be able to:
Describe the COBOL MOVE and assignment operation
List the three types of COBOL assignment statements – and what causes the
COBOL compiler to choose one type over the other
Define the rules for:
 Alphanumeric moves
 Numeric moves
 Group or structure moves
List a few optional MOVE clauses, and describe what they do, including:
 MOVE CORRESPONDING
Code MOVE statements that are syntactically correct
Describe the underlying COBOL storage representation for:
 Alphanumeric data
 Numeric data
List the common COBOL Figurative Constants
Describe what the COBOL INITIALIZE statement does
7
COBOL Picture Clauses and Internal Data Representation
COBOL Data types are PIC clause dependent, and come in several broad categories:

Character Data:
 Fixed Length: PIC X(nn) – or PIC A(nn) … Note, A  "Alphabetic data"
 Stored as EBCDIC bytes – examples: A  Hex: C1, B  Hex: C2, 9  Hex: F9, etc
http://theamericanprogrammer.com/code7302/ebcdic.txt

Numeric Data:
 Display numeric (aka Zoned Decimal): PIC 9(5), PIC S9(5)V99
 Stored as EBCDIC bytes, with "assumed" decimal place – one byte per digit
– Hex values: F0  F9
 With V in declaration – COBOL takes care of decimal alignment in math/MOVE operations
 With S (sign) in declaration, the last byte of internal storage holds the sign (C or D):
–
–
C - is positive number:
– PIC S9(5)V99 - value:
D - is negative number
– PIC S9(5)V99 - value:
321.19 
F0 F0 F3 F2 F1 F1 C9
321.19 
F0 F0 F3 F2 F1 F1 D9
EBCDIC Internal
Data Representation
 Binary (COMP) numeric – used to improve run-time COBOL arithmetic instruction performance:




Small binary: PIC S9(4) COMP – stored in two bytes, pure binary (base 16) data
Medium binary: PIC S9(9) COMP – stored in four bytes
Large binary: PIC S9(18) COMP – stored in eight bytes
With or without Signs, and assumed decimal places:
Ex.
–
–
PIC S9(4) COMP Value
123.
PIC S9(4) COMP Value -123.
Stored as: 0123
Stored as twos complement of 123: FF85
 Packed decimal (COMP-3) numeric – frequently used to reduce the size of a file:

Two digits per/byte. Sign bit – in last "nibble" (bottom 1/2 of last byte). "Slack bytes" (other high-order/leading
zeroes) may need to be added to the internal storage to account for evenly divisible PIC clause + sign nibble
Ex.
–
–
PIC S9(5)V99 COMP-3 Value
PIC S9(5)V99 COMP-3 Value
123.99.
-123.99.
Important – See Slide Notes
Stored as:
Stored as:
8
00 12 39 9C
00 12 39 9D
COBOL Picture Clause Editing and External (Output) Field Values

There are a number of other PIC clauses used for output result data on reports and greenscreen I/O. They are simple to understand, and very convenient. Note that the numeric PIC
clauses force decimal-point alignment. The alphanumeric PIC clauses all align the data left.

Z











Suppress leading zeroes – insert floating blanks
PIC ZZ,ZZZ,Z99.99
B
Alphanumeric "mask" – Positionally insert a blank into alphanumeric data
PIC XBXBXB
0
Numeric "mask" - Positionally insert a zero into a numeric field.
PIC 990990
/
Data mask - Insert a slash into alphanumeric data – typically used for dates
PIC XX/XX/XX
,
Insert a comma into numeric data
PIC Z,ZZZ,Z99.99
.
Insert a decimal point, into numeric data
Z,ZZZ,Z99.99
+
Insert a plus sign – IF the value in the variable is > 0
PIC Z,ZZZ,Z99.99+
Insert a negative sign – IF the value in the variable is < 0
PIC Z,ZZZ,Z99.99CR Insert a "CR" literal – IF the value in the variable is < 0
PIC Z,ZZZ,Z99.99CR
DB Insert a "DB" literal – IF the value in the variable is < 0
PIC Z,ZZZ,Z99.99DB
*
Insert asterisks instead of leading zeros for numeric values
PIC ********9999
$
Dollar-sign suppressions - Insert a floating, left-justified $ sign for numeric values
PIC $$,$$$,$99.99
9
ILE Reference Manual – Picture Clause Editing Examples – 1 of 2

The ILE reference manual has an excellent sample guide to Picture Clause editing

http://publib.boulder.ibm.com/infocenter/iadthelp/v7r0/index.jsp?topic=/com.ibm.etools.iseries.langref.doc/c0925395267.htm
10
ILE Reference Manual – Picture Clause Editing Examples – 2 of 2

The ILE reference manual has an excellent sample guide to Picture Clause editing

http://publib.boulder.ibm.com/infocenter/iadthelp/v7r0/index.jsp?topic=/com.ibm.etools.iseries.langref.doc/c0925395267.htm
11
COBOL Storage Representation – Reference Chart
Picture Clause
Meaning
PIC X(10)
Fixed alpha-numeric data
'ABC'
PIC 9(5)
Display numeric (Zoned Decimal) numbers
-321
00321 - Note - without S (sign)
value get "absolute value"
FFFFF
00321
PIC S9(5)
Zoned decimal - with sign
-321
00321 - Value is negative in math
operations
FFFFD
00321
PIC S9(5)V99
Zoned decimal with implied decimal place
321.5
00321V50
PIC S9(4) COMP
Small binary number - 2 byte - note, negative
binary #s stored as two's complement
321
0321
PIC S9(5) ==> S9(9) COMP
Binary number - 4 bytes
321
00000321
PIC S9(9) ==> S9(18) COMP
Large Binary number
321
000000000000000321
PIC 9(4) COMP-3
Packed decimal number
321
0321
PIC S9(5)V99 COMP-3
Packed decimal number
321.99
00321.99
0319
029C
PIC S9(5)V99 COMP-3
Packed decimal number
-321.99
00321.99 – Value is negative in
math operations
0319
029D
External PIC clauses
Value
Internal Storage
(EBCDIC bytes)
Value
PIC Z(3)
Zero-suppressed
PIC ZZ,ZZZ,ZZZ.99-
Zero-suppressed, with commas and minus sign
-321.99
PIC $$,$$$,$99.99
Dollar-sign suppressed
-321.99
PIC XBXBXB
Blank insertion
ABC
PIC 990990
Zero insertion
-321.99
PIC XX/XX/XX
Slash insertion
012099
PIC Z,ZZZ,Z99.99CR
Zero-suppressed, with commas and Credit sign
-321.99
PIC ****9999
Asterisk suppressed
PIC Z,ZZZ,Z99.99DB
Zero-suppressed, with commas and Debit sign
Internal Value
Output/Display Value
-2.99
-333321.99
321.99
12
CCC4444444
12300000000
ABCbbbbbbb (seven trailing
blanks)
2
FFFFFFC
0032150
04
11
0004
0011
00000004
00000011
031
02F
Notes
No decimal places, no sign
321.99-
Sign on right (can be on left). Zeroes suppressed
$321.99
One resulting $, if need sign, must use dash (-)
AbBbCb
Positional blank (b) inserted
030210
01/10/99
High-order inserted, numbers inserted @ PIC 9
Date mask
321.99CR
**321
321.99
If number was positive, CR would not appear
Like Z and $ - asterisk suppresses leading zeros
If number was negative, DB would appear
88-Level Variables in the Data Division


88-level variables in COBOL programs are "conditionals, built in to the variable
declarations"
They:
 Have no PIC clause
 Have one or more VALUES – specified as literals (see a few valid expressions below)
 Are used effectively to make COBOL IF conditional expressions readable/maintain-able
01 MONTH-IND PIC XXX.
88 SHORTEST-MONTH
VALUE 'FEB'.
88 THIRTY-DAY-MONTH
VALUES ARE 'JUN', 'SEP', 'APR', 'NOV'.
88 THIRTY-ONE-DAY MONTH
VALUES ARE 'JAN' 'MAR' 'MAY' 'JUL' 'AUG' 'OCT' 'DEC'.
…
IF THIRTY-DAY-MONTH
…
01 STUDENT-GRADE-RANGE PIC S9(3).
88 A-OK
VALUE 90 THRU 100.
88 NOT-BAD
VALUE 80 THRU 89.
88 PRETTY-GOOD VALUE 70 THRU 79.
88 RUH-ROH
VALUE 60 THRU 79.
88 FAIL
VALUE 0 THRU 59.
…
IF NOT-BAD
MOVE 'DOIN ALRIGHT' TO MSG-TEXT
DISPLAY GRADE-MSG
13
Pluses:
• Make code more "English" read-able
• Allow you to centralize conditions in one place - in
the DATA DIVISION
Minuses:
• Force you to refer to the DATA DIVISION for the
actual values tested in the code in the PROCEDURE
DIVISION
Review – Imperative Statements – MOVE
FILE SECTION
…
01
OUT-REC
PIC X(80).
…
WORKING-STORAGE SECTION.
77
INPUT-DATA
PIC X(40).
…
PROCEDURE DIVISION.
…
ACCEPT INPUT-DATA.
MOVE INPUT-DATA TO OUT-REC.
Syntax:


MOVE
<to-variable> TO <from-variable>.
MOVE copies the value in the to-variable to the from-variable (receiving
field), over-writing the from-variable’s storage contents.
There are two types of MOVE operations:
 Alphanumeric MOVE
 Numeric MOVE


The receiving field's datatype (PIC clause) dictates the type of MOVE operation
It is important to understand how the contents of variable storage are affected by
MOVE. So, let's drill-down now, on PIC clauses and COBOL internal data
storage representation
14
Alphanumeric MOVE Statements
Alphanumeric MOVE statements:
 Occur when the receiving field is considered Alphanumeric by the compiler



PIC X
PIC A
The Alphanumeric formatted output PIC clauses:
– PIC with B, etc.
 Proceed from left-to-right – and copy byte-for-byte

When the sending and receiving fields are not the same size:
 Space (blank) fill to the right, if the receiving field is longer than the sending field
 Truncate if the receiving field is shorter than the sending field (typically you will get a W-level diagnostic
when you compile a program with a MOVE statement that truncates data)
 Except – can JUSTIFY the receiving field data RIGHT






FLD1
FLD2
…
MOVE
PIC X(4) VALUE 'ABCD'.
PIC X(10) JUSTIFY RIGHT.
FLD1 TO FLD2.
– Results in FLD2 value of: bbbbbbABCD
If JUSTIFY RIGHT, and the receiving field is shorter than the sending field, truncation occurs in the right-most
characters
If JUSTIFY RIGHT, and the receiving field is longer than the sending field, blanks are added to the left-most
positions
Note: if, FLD1 PIC X(10) VALUE 'ABCD' result of MOVE is: ABCDbbbbbb.
– Why?
 Copy:



Internal storage values byte for byte
For the # of bytes in the receiving field
Group data (structures) are considered Alphanumeric – in MOVE operations
15
Numeric MOVE Statements
 Numeric MOVE statements:
 Occur when the receiving field's PIC clause is numeric
 9 … anywhere in the PIC clause
 Input field declaration:
– V, S
 Output (formatted numeric PIC clause in declaration)
– Z, $, 0, DB, CR, +, -, period (.), comma (,)
 MOVE copies the algebraic value of the sending field to the
receiving field as follows:
 Automatically aligns at the decimal place
 Or assumed decimal place if no V in PIC clause
 Pad to the left with leading, and to the right with trailing zeroes, if the receiving field has
more decimal digits to the left or the right of the (assumed) decimal positions
 If sign (S) or numeric edited sign MOVE will value the receiving positively or negatively
depending on the sending field's value. If no sign, the receiving field gets absolute value
 Will numerically truncate – if receiving field has fewer decimal digits to the left of the
decimal place, or less digits (decimal precision) to the right of the decimal place
What about mixed datatype MOVE statements? (next slide…)
16
MOVE Statements When the Datatypes Are Not The Same

Obviously you can move PIC X fields to other PIC X – and PIC 9 fields to other PIC 9
fields, but sometimes, due to business requirements you will have to code MOVE
statements of unlike (mixed) datatypes.

Here are the general rules:





Anything can be moved to an alphanumeric PIC X field
Only other PIC 9 (input) fields can be moved to PIC 9 fields
And only PIC 9 fields can be moved to numeric edited fields
PIC 9 numeric edited fields can be moved to PIC 9 fields
Group moves are considered exactly the same as an alphanumeric PIC X field move by the
compiler
 And all the rules you just learned about truncation, padding and decimal alignment also apply
 This table may help clarify the rules for mixed data type MOVE
Sending
Fields
Receiving Fields
PIC X
PIC 9
Numeric
Edited
PIC X
Y
N
N
PIC 9
Y
Y
Y
Y
N
Treated as an alphanumeric MOVE
(digits may be lost, trailing blanks
may be added, etc.)
Numeric Edited
Y
17
Allowable
MOVE Statements

Please
consult this
verbose (!)
table to see
the complete
list of COBOL
allowable
MOVE
statements –
based on
sending and
receiving field
PIC types.

Don't worry if
there are
terms you're
not up to
speed on just
yet – we'll get
you there.

Patience 
18
Alphanumeric MOVE Statements - Examples
Sending Field
Receiving Field
Sending Field Value
Result in Receiving
Field
PIC X(5)
PIC X(5)
ABCDE
ABCDE
PIC X(5)
PIC X(3)
ABCDE
ABC
PIC X(5)
PIC X(8)
ABCDE
ABCDEbbb
PIC 9(5)
PIC X(8)
12345
12345bbb
PIC X(5)
PIC 9(5)
Not allowed by the compiler
N/A
PIC S9(5)V99 COMP-3
PIC X(8)
Not allowed by the compiler – as is noninteger numeric (see table of moves)
13574444
246C0000
PIC S9(4) COMP
PIC X(4)
1234
1344
2400
PIC X(4)
PIC X(10) JUSTIFY RIGHT.
ABCD
bbbbbbABCD
(hex)
Numeric Value
PIC 9(5)V99
PIC 9(3)V9
12345.67
345.67
PIC S9(7)V99
PIC 9(4) COMP
123456789.99
6789
PIC S9(5)V99
PIC S9(7)V999 COMP-3
-12345.67
0012345.670 (minus carried in sign bit)
PIC S9(9) COMP
PIC 9(5)V99
1234567912
67912.00
PIC S9(5)V99 COMP-3
PIC 9
-12345.67
5
CUSTOMER-NAME
PIC X(18)
SMITHbbbbbAALEXAND
CUSTOMER-RECORD
PIC X(40)
1201SMITHbbbbbAALEXANDERbbbbbbbbbbbbbbbbbbbbbb
Group Moves
01 CUSTOMER-RECORD.
05 ID-NUMBER
05 CUST-TYPE
05 CUSTOMER-NAME.
10 FIRST-NAME
10 MIDINIT
10 LAST-NAME
PIC 9(2)
PIC 9(2)
VALUE 12.
VALUE 01.
PIC X(10) VALUE 'SMITH'.
PIC X(01) VALUE 'A'.
PIC X(10) VALUE 'ALEXANDER'.
19
MOVE With OF Modifier
FILE SECTION.
…
01 CUSTOMER-RECORD-IN.
05 ID-NUMBER
PIC 9(2).
05 CUST-TYPE
PIC 9(2).
05 CUSTOMER-NAME.
10 FIRST-NAME
PIC X(10).
10 MIDINIT
PIC X(01).
10 LAST-NAME
PIC X(10).
01 CUSTOMER-RECORD-OUT.
05 ID-NUMBER
PIC 9(2).
05 CUST-TYPE
PIC 9(2).
05 CUSTOMER-NAME.
10 FIRST-NAME
PIC X(10).
10 MIDINIT
PIC X(01).
10 LAST-NAME
PIC X(10).
…
PROCEDURE DIVISION.
MOVE FIRST-NAME OF CUSTOMER-RECORD-IN TO FIRST-NAME OF CUSTOMER-RECORD-OUT.

Syntax:

The OF modifier allows you to:


MOVE <from-variable> of <from-Group> to
<to-variable>.
Fully-qualify elementary field names – making large programs with 1,000's variables easier to maintain
Compile programs with duplicate elementary field names
20
MOVE CORRESPONDING
FILE SECTION.
…
01 CUSTOMER-RECORD-IN.
05 ID-NUMBER
PIC 9(2).
05 CUST-TYPE
PIC 9(2).
05 CUSTOMER-NAME.
10 FIRST-NAME
PIC X(10).
10 MIDINIT
PIC X(01).
10 LAST-NAME
PIC X(10).
01 CUSTOMER-RECORD-OUT.
05 ID-NUMBER
PIC 9(2).
Field's data not moved
05 CUSTTYP
PIC 9(2).
05 CUSTOMER-NAME.
Field's data not moved
10 FIRSTNAME
PIC X(10).
10 MIDINIT
PIC X(01).
10 LAST-NAME
PIC X(10).
…
PROCEDURE DIVISION.
MOVE CORRESPONDING CUSTOMER-RECORD-IN TO CUSTOMER-RECORD-OUT.

Syntax:

The CORRESPONDING modifier allows you to MOVE group records:
MOVE CORRESPONDING <from-group-variable> to
<to-group-variable>.
 When COBOL variable names match between the from and to groups, data is copied
 And only when COBOL variable names match
21
See Notes
COBOL INITIALIZE Statement

INITIALIZE values selected types of data fields. The default is:
 Numeric data to zeros
 alphanumeric data (PIC X or Group Data Items) to spaces.

You can also INITIALIZE fields, replacing classes of datatypes with specific values
 This is used less frequently, and is shown in the

slide notes
Initializing a structure (INITIALIZE)
 You can reset the values of all subordinate data items in a group item by applying the
INITIALIZE statement to that group item.
22
COBOL Figurative Constants
FILE SECTION.
…
01 CUSTOMER-RECORD-IN.
…
77 COBOL-CHAR-FIELD
77 COBOL-NUM-FIELD
77 COBOL-QT
PROCEDURE DIVISION.
MOVE LOW-VALUES
MOVE HIGH-VALUES
MOVE SPACES
MOVE ZEROS
MOVE ALL '_'
PIC X(4).
PIC 9(4).
PIC X(1) VALUE QUOTE.
to
to
to
to
TO
CUSTOMER-RECORD-IN.
COBOL-CHAR-FIELD.
COBOL-CHAR-FIELD.
COBOL-NUM-FIELD.
COBOL-CHAR-FIELD.

Syntax:

There are a number of COBOL figurative constants available to fill the storage of
alphanumeric fields (or in the case of ZEROS), either:
MOVE <figurative constant> to
<Cobol variable>.
 With MOVE statements
 In VALUE clauses of field declarations


The figurative constants are reserved words, and there are a number of alternative spellings
(see the COBOL language reference, or RDz Help system)
They are sometimes used by convention to signal some processing event:
 READ <fileName>
AT END MOVE HIGH-VALUES TO <inputRecord>.
23
COBOL Literal Values
FILE SECTION.
…
01 CUSTOMER-RECORD-IN.
…
77 COBOL-CHAR-FIELD
77 COBOL-NUM-FIELD
PROCEDURE DIVISION.
MOVE "My literal"
MOVE 'My literal'
MOVE 99.34
MOVE 11134
PIC X(40).
PIC 9(7)V99 COMP-3.
to
to
to
TO
COBOL-CHAR-FIELD.
COBOL-CHAR-FIELD.
COBOL-NUM-FIELD.
COBOL-NUM-FIELD.
MOVE <literal> to
<Cobol variable>.

Syntax:


COBOL literal values can be numeric – or string (text – or PIC X) values
Numeric values are coded as numbers
 Only digits – including the decimal point if needed, but excluding commas to separate the
hundreds/thousands, etc.
 Note that if numeric decimal values are used as literals, you must specify at least one digit to the left of
the decimal place:
 0.123 …NOT… .123

String values must be enclosed in either:
 Double-quotes "
 Single-quotes '
24
Lab Assignment
From the course workshop documents, do the following labs:
1. Data Representation and assignment (MOVE statement) Lab
2. Open ended workshop
25
Unit
COBOL General Language
Rules
Topics:
 Assignment Statements and Internal Data
Representation
 Math Operations
 Conditional Logic
 Transfer of control
 COBOL Looping Constructs
 Sequential File Processing Patterns
 Java and .NET Equivalents
26
COBOL Mathematical Operators
 As you'd expect from a a business oriented language, COBOL's math
capabilities are simple, flexible, deep and robust.
Simple operations:




ADD
SUBTRACT
MULTIPLY
DIVIDE
…with a number of variations of operand/operator expressions and automatic decimal
alignment across all numeric types
Algebraic statements:
 COMPUTE – uses arithmetic operators (next slide) to perform math operations
COBOL Intrinsic "Built-in" math Functions
 Here are a few of the math-oriented COBOL intrinsic functions:
ACOS
ANNUITY
ASIN
ATAN
CHAR
COS
FACTORIAL
LOG
LOG10
MAX
MEAN
MEDIAN
MIDRANGE
MIN
MOD
PRESENT-VALUE
RANDOM
27
RANDOM
RANGE
REM
REVERSE
SIN
SQRT
STANDARD-DEVIATION
SUM
TAN
VARIANCE
Fixed-Point Arithmetic Statements*** – ADD
WORKING-STORAGE SECTION.
01 WORK-FIELDS.
05 ITEM-1 PIC S9(3)V99 VALUE 85.52.
05 ITEM-2 PIC S9(3)V99 VALUE 2.34.
05 SUM
PIC S9(5)V99 VALUE 0.
PROCEDURE DIVISION.
…
ADD ITEM-1, ITEM-2 TO SUM ROUNDED
ON SIZE ERROR MOVE 0 TO SUM
END-ADD
ADD ITEM-1 ITEM-2 GIVING SUM ROUNDED
ON SIZE ERROR MOVE 0 TO SUM
DISPLAY '** ON SIZE ERROR **'
END-ADD

Format 1

Rounded
 Rounds to the decimal digits in
the PIC clause (See Slide Notes)

ON SIZE ERROR
 Allows you to handle arithmetic
overflow conditions with
imperative statements.

Additional note: You can
substitute a numeric literal for the
variables in the ADD and TO (but
not GIVING) clauses in the
statement
 Adds the addend to the sum

Format 2
 The values of all operands preceding the word GIVING are added together, and the
sum is stored as the new value.
 None of the values in the operands preceding GIVING are changed

Note: There is a Format 3 statement: ADD CORRESPONDING
28
***See Notes
Arithmetic Statements – ROUNDED and ON SIZE ERROR
WORKING-STORAGE SECTION.
01 WORK-FIELDS.
05 ITEM-1 PIC S9(5)V99 VALUE 85.56.
05 RESULT PIC S9(6)
VALUE 100.
PROCEDURE DIVISION.
…
ADD ITEM-1 TO RESULT. 
Value: 185 
MOVE 100 TO RESULT.
ADD ITEM-1 TO RESULT ROUNDED. 
Value: 186
The ROUNDED phrase allows you to specify rounding up to the
nearest low-order decimal digit of precision. This means that
ROUNDED adds 1 to the absolute value of the low-order digit of
the result variable IF the absolute value of the next least
significant digit of the intermediate variable value is >= to 5.
MOVE 140156.33 TO ITEM-1.
MOVE 900000 TO RESULT.
ADD ITEM-1 TO RESULT ROUNDED. 
Value: 040156 
MOVE 900000 TO RESULT.
ADD ITEM-1 TO RESULT
ON SIZE ERROR MOVE 0 TO SUM 
DISPLAY '** ON SIZE ERROR **'.
29
Value: 000000
Arithmetic Statements – SUBTRACT
WORKING-STORAGE SECTION.
01 WORK-FIELDS.
05 ITEM-1
PIC S9(3)V99 VALUE 85.52.
05 ITEM-2
PIC S9(3)V99 VALUE 2.34.
05 DIFFERENCE
PIC S9(5)V99 VALUE 0.
PROCEDURE DIVISION.
…
SUBTRACT ITEM-1, ITEM-2 FROM DIFFERENCE ROUNDED
ON SIZE ERROR MOVE 0 TO DIFFERENCE
END-SUBTRACT
SUBTRACT ITEM-1 FROM ITEM-2 GIVING DIFFERENCE ROUNDED
ON SIZE ERROR MOVE 0 TO DIFFERENCE
DISPLAY '** ON SIZE ERROR **'
END-SUBTRACT




Rounded


ON SIZE ERROR


Rounds to the decimal
digits in the PIC clause
Allows you to handle
arithmetic overflow
conditions with imperative
statements.
Additional note: You
can substitute a numeric
literal for the variables in
the SUBTRACT and FROM
(but not GIVING)
clauses in the statement
Format 1
 Subtracts all minuends from the sum
Format 2
 The values of all operands preceding the word GIVING are added together, and the
sum is subtracted from the difference (in the above)
 None of the values in the operands preceding GIVING are changed
Note: There is a Format 3: SUBTRACT CORRESPONDING
30
Arithmetic Statements – MULTIPLY
WORKING-STORAGE SECTION.
01 INPUT-FIELDS.
05 ITEM-1
PIC S9(3)V99 VALUE 85.52.
05 ITEM-2
PIC S9(3)V99 VALUE 2.34.
05 ITEM-3
PIC S9(3)V99 VALUE 6.01.
05 RESULT
PIC S9(5)V99.
PROCEDURE DIVISION.
MULTIPLY ITEM-1 BY ITEM-3 ROUNDED
ON SIZE ERROR MOVE 0 TO DIFFERENCE
END-MULTIPLY
MULTIPLY ITEM-1 BY ITEM-2 GIVING RESULT ROUNDED
ON SIZE ERROR MOVE 0 TO DIFFERENCE
DISPLAY '** ON SIZE ERROR **'
END-MULTIPLY


Format 1
 The values of the operand preceding the word BY is multiplied by the operand after
the word BY
Format 2
 The value of the operand after the word GIVING is replaced by the multiplication of
ITEM-1 BY ITEM-2
 None of the values in the operands preceding GIVING are changed
31
Arithmetic Statements – DIVIDE – Common Usage and Formats
WORKING-STORAGE SECTION.
01 INPUT-FIELDS.
05 ITEM-1
PIC S9(3)V99 VALUE 85.52.
05 ITEM-2
PIC S9(3)V99 VALUE 2.34.
05 ITEM-3
PIC S9(3)V99 VALUE 6.01.
05 RESULT
PIC S9(5)V99.
PROCEDURE DIVISION.
DIVIDE ITEM-1 INTO ITEM-3 ROUNDED
ON SIZE ERROR MOVE 0 TO DIFFERENCE
END-DIVIDE
DIVIDE ITEM-1 INTO ITEM-2 GIVING RESULT ROUNDED
ON SIZE ERROR MOVE 0 TO DIFFERENCE
DISPLAY '** ON SIZE ERROR **'
END-DIVIDE
DIVIDE ITEM-1 BY ITEM-3 ROUNDED
REMAINDER ITEM-3
END-DIVIDE
DIVIDE ITEM-1 INTO ITEM-2 GIVING RESULT ROUNDED
REMAINDER ITEM-3
END-DIVIDE

Five separate Formats for DIVIDE (see Slide Notes)
32

Rounded


ON SIZE ERROR


Rounds to the decimal
digits in the PIC clause
Allows you to handle
arithmetic overflow
conditions with imperative
statements.
Additional note: You
can substitute a numeric
literal for the variables in
the DIVIDE, BY and
INTO, (but not GIVING)
clauses in the statement
Arithmetic Statements – COMPUTE
WORKING-STORAGE SECTION.
…
01 INPUT-FIELDS.
05 ITEM-1
PIC S9(3)V99 VALUE 85.52.
05 ITEM-2
PIC S9(3)V99 VALUE 2.34.
05 ITEM-3
PIC S9(3)V99 VALUE 6.01.
05 RESULT
PIC S9(5)V99.
PROCEDURE DIVISION.
…
COMPUTE RESULT ROUNDED =
(ITEM-1 * ITEM-2 / ITEM-3).
Note:
Blanks (the white space) between elements
of your equation are significant with COMPUTE.
For example:
Compute celsius rounded =
(5/9) * (fahrenheit - 32).
Compute celsius rounded =
( 5 / 9 ) * (fahrenheit - 32).
--- will not work
--- will work
 The COMPUTE statement assigns the value of an arithmetic (think algebraic)
expression to one or more data items.
 It allows you to combine arithmetic operations without the restrictions on
receiving data items that the rules for the ADD, SUBTRACT, MULTIPLY, and
DIVIDE statements impose.
 When you need to combine arithmetic operations, using the COMPUTE
statement may be more efficient than writing a series of separate arithmetic
statements.
 You may use any of the arithmetic operators shown on the next slide inside a
compute statement
 Additionally, you can combine COMPUTE with COBOL intrinsic functions
33
COMPUTE Arithmetic Operators
 Use the above arithmetic operators to in your COMPUTE statements
 The operations proceed as follows:
 Unary Operators
 Multiplication/Division/Exponentiation
 Addition/Subtraction
… from left to right within the COMPUTE – and following the order of parenthesis
 Thus, it's always a good idea to force an explicit arithmetic order of
precedence using parenthesis in COMPUTE statements
These two statements are not algebraically equivalent:
COMPUTE RESULT ROUNDED =
(ITEM-1 * ITEM-2 + ITEM-3).
COMPUTE RESULT ROUNDED =
(ITEM-1 * (ITEM-2 + ITEM-3)).
34
Intermediate Results of Fixed Point Math
From the IBM Enterprise COBOL Programmer's Guide - Document Number: SC23-8529-00



The compiler handles arithmetic statements as a succession of operations performed according to operator
precedence, and sets up intermediate fields to contain the results of those operations.
The compiler uses algorithms to determine the number of integer and decimal places to reserve.
Intermediate results are possible in the following cases:






In an ADD or SUBTRACT statement that contains more than one operand immediately after the verb
In a COMPUTE statement that specifies a series of arithmetic operations or multiple result fields
In an arithmetic expression contained in a conditional statement or in a reference-modification specification
In an ADD, SUBTRACT, MULTIPLY, or DIVIDE statement that uses the GIVING option and multiple result fields
In a statement that uses an intrinsic function as an operand
The precision of intermediate results also depends on whether you compile using the default option
ARITH(COMPAT) or using ARITH(EXTEND)
Net:
 Because of the effect of the intermediate results on your arithmetic calculations can produce incorrect
results (mostly truncation errors)
 And because the above list is a lot to remember (and is actually only the entry point into the topic)!
 You can – and should follow these simple rules-of-thumb:


Be particularly careful to define your numeric datatypes to the precision necessary for your requirements
When using literals in your calculations always add the necessary decimal digits of precision to them, in order to
force the compiler to create intermediate results to your level of requirements
Example: Instead of: COMPUTE FIELD-1 ROUNDED = 100 * (32.78 / 1000).

Include decimal places in your literals:
COMPUTE FIELD-1 ROUNDED = 100.000 * (32.78 / 1000.000).
35
Lab Assignment
From the course workshop documents, do the following labs –
create and debug COBOL program that calculates simple
interest based on the following variables
amount
principal
interest
nbrYears
PIC
PIC
PIC
PIC
9(7)V99.
9(7)V99.
9(2)V99.
9(4) COMP.
//Business logic – in pseudo-code.
//Initialize values
amount = 0;
principal = 10000.01;
interest = .05;
nbrYears = 10;
//Invoke simple interest calculation function
calculateSimpleInterest();
end
function calculateSimpleInterest()
amount = principal * (1 + (nbrYears * interest));
end
end
36
Unit
COBOL General Language
Rules
Topics:
 Assignment Statements and Internal Data
Representation
 Math Operations
 Conditional Logic
 Transfer of control
 COBOL Looping Constructs
 Sequential File Processing Patterns
 Java and .NET Equivalents
37
COBOL Conditional Expressions
 Two statement options:
IF/ELSE
EVALUATE statement
 Both useful – and have many language patterns and options (you'll see  )
 In general:
Use IF for coding:
 Simple expressions
 Conditional statements with tests against multiple fields
 Complex statements – with tests against multiple fields
Use EVALUATE for:
 Implementing "decision table" logic
 Coding statements with multiple tests against a single field
 Let's take a close look at both statements
See Slide Notes
38
Conditional Statements – IF Statement Overview
 IF statement has two operational modes:
IF
condition
Alphanumeric compare:
 On variables of type:
ELSE
Statement
Block
– PIC X
– PIC A
– Group data items
THEN
Statement
Block
– Alphanumeric literal
 EBCDIC (or ASCII) value "byte-for-byte"
comparison
END-IF
– Comparison proceeds from Left-to-Right
– Alphanumeric range ( < or > ) is based on
platform's collating sequence
 Shorter fields are padded with spaces
(HEX '40') to length of longer variable
– Regardless of which side of the IF statement is shorter/longer
Numeric comparison:
 On variables of type PIC 9 or a numeric literal
 Algebraic compare
 Decimal positions automatically aligned
 Note that overall, the IF statement comparison values must be "data type compatible"
39
the
IF Statement Examples
Simple IF - No ELSE
IF/ELSE
Note – matching END-IF for each
IF/ELSE
"Nested" IF/ELSE
Nested IF/ELSE refactored as IF with
AND connectors
Note – only one END-IF
IF POLICY-OVERDUE-DAYS > 90
ADD +100 TO AMT-DUE
END-IF
_____________________________________________________________________
IF EMPLOYEE-SALARY-TYPE = "H"
PERFORM 400-PROCESS-HOURLY-PAY
ELSE
IF
EMPLOYEE-SALARY-TYPE = "S"
PERFORM 400-PROCESS-SALARIED-PAY
ELSE
MOVE "***" TO EMPLOYEE-SALARY-TYP
ADD +1 TO ERRORS-FOUND-KTR
END-IF
END-IF
_____________________________________________________________________
IF HOURS-WORKED > 40
IF HOURLY-EMPLOYEE = "Y"
IF NO-ERRORS-FOUND
PERFORM 900-CALCULATE-HOURLY-OT
END-IF
END-IF
END-IF
_____________________________________________________________________
IF HOURS-WORKED > 40 AND
HOURLY-EMPLOYEE = "Y" AND
NO-ERRORS-FOUND
PERFORM 900-CALCULATE-HOURLY-OT
END-IF
40
COBOL Conditional Statements – IF Statement Overview


Condition may be simple or complex (> 1 simple condition)
There are five simple conditions, which have a truth value of
either true or false:
1.
Class condition:

2.
Condition-name condition:

3.
4.
88-LEVEL Data Items
Relation condition (value-based comparisons)
Sign condition

5.
ALPHABETIC, NUMERIC, ALPHABETIC-UPPER
POSITIVE, NEGATIVE, ZERO
Switch-status condition – used with SPECIAL NAMES (rare)

Use Content-Assist (Ctrl/Spacebar) to view options 

A complex condition is formed by combining simple
conditions, combined conditions, and/or complex conditions
with logical operators, or negating these conditions with logical
negation:
 AND
 OR
 NOT
If complex condition, comparisons proceed from Left-to-Right:
 But you can (and most of the time should) specify your own
comparison operation precedence by surrounding separate
conditions with parenthesis to make the logic apparent


To humans who read/maintain your code, as well as to the compiler
41
See Notes
IF/ELSE – Examples – and See Slide Notes
FILE SECTION
…
01
OUT-REC
PIC X(80).
…
WORKING-STORAGE SECTION.
77
ITEM-1
PIC X(12).
77
ITEM-2
PIC X(15).
77
ITEM-3
PIC 9(05).
88 VALID-ITEM
VALUES ARE 11111, 22222.
…
PROCEDURE DIVISION.
Simple
IF ITEM-1 > "10"
Relation
Condition
MOVE "X" TO ITEMB
ELSE
PERFORM PROC-A
END-IF
IF ITEM-1 NUMERIC
MOVE ITEM-1 TO ITEM-3
END-IF
Class
Condition
IF VALID-ITEM
Condition-Name
Condition
MOVE ITEM-2 TO ITEM-1
ELSE
MOVE FUNCTION UPPER-CASE(ITEM-2)
TO ITEM-1
END-IF
Complex
Nested IF
Relation
Condition
IF ( ITEM-3 IS POSITIVE ) AND
( ITEM-1 NOT > ITEM-2 )
THEN IF ITEM-3 = 22222
THEN DISPLAY "22222-RECORD"
ELSE DISPLAY "11111-RECORD"
END-IF
ELSE DISPLAY "BAD RECORD"
END-IF
Complex
IF ITEM-1 > "10"
Nested IF
Relation
IF ITEM-1 = ITEM-2
Condition
ADD 1 TO ITEM-3
MOVE ALL "X" TO OUT-REC
END-IF
MOVE "X" TO ITEM-2
END-IF
IF NOT (ITEM-3 < 10 OR ITEM-3 > 500)
AND ITEM-1 <= "Z"
Complex
Nested IF
THEN DISPLAY "Done"
Condition
END-IF
Combing
OR/AND
42
Implied IF Condition Statements
 When referring to the same field on
both sides of a compound condition,
you do not have to repeat the variable
name
 Example:
IF EMPLOYEE-ID > 20
AND EMPLOYEE-ID < 3000
Can be coded as:
IF EMPLOYEE-ID > 2000 AND < 3000
IF ITEM-2 = "AABBCC" OR "AACCDD"
OR "AADDEE"
MOVE ITEM-2 TO ITEM-1
ELSE
MOVE FUNCTION UPPER-CASE(ITEM-2)
TO ITEM-1
END-IF
IF NOT (ITEM-3 < 10 OR > 500)
ITEM-1 <= "Z"
THEN DISPLAY "Done"
END-IF
There is no hard and fast rule (or even
rule-of-thumb) on this coding idiom.
Pluses:
 Creates more compact easily code
 Can be more easily readable
AND
Examples of implied IF statement conditions
Minuses
 Written semantics are not as exact and
explicit
– Many modern languages do not permit this
 Might be misunderstood if merely
browsing or scanning code
IF ITEM-1 NUMERIC AND > 10000
MOVE ITEM-1 TO ITEM-3
END-IF
43
Bypassing Conditional Logic (NEXT SENTENCE and CONTINUE)
 There are two standard ways for you to skip
over logic in a complex IF statement that you
must avoid as per business requirements
 Code (after the if condition) either:
IF ITEM-2 ALPHABETIC-UPPER
NEXT SENTENCE
ELSE
MOVE FUNCTION UPPER-CASE(ITEM-2)TO ITEM-1
ADD +10 TO AMOUNT-SUB-TOTAL
END-IF
ADD +1 TO REC-KTR
ADD REC-TOTAL TO WS-TOTAL-CLAIMS-PYMNTS
WRITE OUTPUT-RECORD FROM WS-OUT-REC.
NEXT SENTENCE – which branches to
the next sequential statement after an
ending period
…or…
CONTINUE – which branches to the next
sequential statement after an ending period
– OR the IF statement's scope terminator.
GOBACK.
 An important distinction – to be sure 
 Because NEXT SENTENCE is looking for
the next physical period in the source – and
scope-terminators/indentation mean
nothing whatsoever to it, you will probably
want to use: CONTINUE – if you're coding
style is to use scope-delimiters (a best
practice).
 Note also that, when you're coding new
programs this is not as problematic as
when you are maintaining existing COBOL
applications
IF ITEM-2 ALPHABETIC-UPPER
CONTINUE
ELSE
MOVE FUNCTION UPPER-CASE(ITEM-2)TO ITEM-1
ADD +10 TO AMOUNT-SUB-TOTAL
END-IF
ADD +1 TO REC-KTR
ADD REC-TOTAL TO WS-TOTAL-CLAIMS-PYMNTS
WRITE OUTPUT-RECORD FROM WS-OUT-REC.
GOBACK.
What if I want to bypass more than
the current logic statement block?
See Slide Notes
44
Conditional Statements – EVALUATE Statement
 The EVALUATE statement is COBOL's version of
the (in other programming languages) "case" or
"switch) statement.
 EVALUATE provides a shorthand notation for a
series of nested IF statements.
 When your program has to test a single variable
for more than two values, EVALUATE is probably a
better choice than nest IF
 See next slide
 EVALUATE parses a variable value
 WHEN is used as the condition expression
EVALUATE
Statement
WHEN
condition
TRUE
Statement
Block
WHEN
condition
…
 You can a single WHEN condition
 You can use multiple WHEN statements when several
WHEN
conditions lead to the same processing action
OTHER
 You can use a WHEN <value> THRU <value> phrase
to easily code several conditions in a range of
values
 You can specify "TRUE" or "FALSE" as the testing
criteria – and can combine with "ALSO"
END-EVALUATE
45
TRUE
Statement
Block
TRUE
Statement
Block
EVALUATE versus Nested IF Statement Comparison
Example 1
IF CARPOOL-SIZE = 1 THEN
MOVE "SINGLE" TO PRINT-CARPOOL-STATUS
ELSE
IF CARPOOL-SIZE = 2 THEN
MOVE "COUPLE" TO PRINT-CARPOOL-STATUS
ELSE
IF CARPOOL-SIZE >= 3 and
CARPOOL-SIZE <= 6 THEN
MOVE "SMALL GRP" TO PRINT-CARPOOL-STATUS
ELSE
MOVE "BIG GRP" TO PRINT-CARPOOL-STATUS
END-IF
END-IF
END-IF
EVALUATE CARPOOL-SIZE
WHEN 1
MOVE "SINGLE" TO PRINT-CARPOOL-STATUS
WHEN 2
MOVE "COUPLE" TO PRINT-CARPOOL-STATUS
WHEN 3 THRU 6
MOVE "SMALL GRP" TO PRINT-CARPOOL STATUS
WHEN OTHER
MOVE "BIG GRP" TO PRINT-CARPOOL STATUS
END-EVALUATE
Example 2
IF MARITAL-CODE = "M" THEN
ADD 2 TO PEOPLE-COUNT
ELSE
IF MARITAL-CODE = "S"
OR MARITAL-CODE = "D"
OR MARITAL-CODE = "W"
THEN ADD 1 TO PEOPLE-COUNT
END-IF
END-IF
EVALUATE MARITAL-CODE
WHEN "M" ADD 2 TO PEOPLE-COUNT
WHEN "S"
WHEN "D"
WHEN "W" ADD 1 TO PEOPLE-COUNT
END-EVALUATE
46
Conditional Statements – EVALUATE – Complex Examples
FILE SECTION
…
01
OUT-REC
PIC X(80).
…
Working-Storage Section.
01 Age
PIC 999.
01 Sex
PIC X.
01 Description PIC X(15).
01 A
PIC 999.
01 B
PIC 9999.
01 C
PIC 9999.
01 D
PIC 9999.
01 E
PIC 99999.
01 F
PIC 999999.
Evaluate True Also True
When Age < 13 Also Sex = "M"
Move "Young Boy" To Description
When Age < 13 Also Sex = "F"
Move "Young Girl" To Description
When Age > 12 And Age < 20 Also Sex = "M"
Move "Teenage Boy" To Description
When Age > 12 And Age < 20 Also Sex = "F"
Move "Teenage Girl" To Description
When Age > 19 Also Sex = "M"
Move "Adult Man" To Description
When Age > 19 Also Sex = "F"
Move "Adult Woman" To Description
When Other
Move "Invalid Data" To Description
End-Evaluate
Evaluate True Also True
When A + B < 10 Also C = 10
Move "Case 1" To Description
When A + B > 50 Also C = ( D + E ) / F
Move "Case 2" To Description
When Other
Move "Case Other" To Description
End-Evaluate
"True ALSO True" means that both conditions in the WHEN clause must be true
to take the WHEN path
47
Lab Assignment
From the course workshop documents, do the following labs:
1. Conditionals Lab
48
Unit
COBOL General Language
Rules
Topics:
 Assignment Statements and Internal Data
Representation
 Math Operations
 Conditional Logic
 Transfer of control
 COBOL Looping Constructs
 Sequential File Processing Patterns
 Java and .NET Equivalents
49
Topic objectives
By the end of this unit you should  Understand how the PERFORM can be used to transfer control to block of
code contained in a paragraph or section..
 Know how to use the PERFORM..THRU and the GO TO and understand
the restrictions placed on using them.
 Understand the difference between in-line and out-of-line Performs
50
COBOL Transfer of Control Options
 Three keywords used to transfer control in traditional COBOL
PERFORM
 Branches to the first statement in a block of code
– Inline
– Or, organized in a labeled paragraph or section somewhere else in the PROCEDURE DIVISION
 At the end of the performed code, control is automatically returned to the next
sequential instruction following PERFORM
 PERFORM is a statement with a number of useful options and extensions
GO TO
 Unconditional branch to a labeled paragraph or section
 All statements are executed at that point in time – forward in the program
CALL
 Invoke another COBOL program
 Pass parameters with a USING statement
 We will discuss CALL in a future section of this course
 Of the above three options:
PERFORM and CALL are best practices for "structured programming"
GO TO is not a best practice, but we will present it, as you will see many
examples of GO TO in production COBOL, and need to understand it
51
PERFORM – External Paragraph or Section
 Structured coding method of branching to – and
returning from COBOL paragraphs or sections
 With PERFORM, the compiler automatically returns
control to the "next sequential instruction" after the
block of statements in the paragraph or section ends
 This makes the program's flow of control easy to read,
easy to understand and easy to maintain
 Less worry about "fall thru" logic
 PERFORM
 May be nested:
 This is known as a "PERFORM chain" – or a series of
PERFORM
and return branches controlled by the
Operating System at run-time.
 May NOT be recursive:
 In this example, within 200-OPEN-FILES you may
not PERFORM 100-HOUSEKEEPING
 Does not depend on physical placement or ordering in
the source files:
 Although it can help from a read-ability standpoint
to PERFORM paragraphs lower (down) in the
program listing.
 Allows you do "divide and conquer" the design and
development of large complex applications.
 Do not scope external paragraph PERFORM
with END-PERFORM
52
PROCEDURE DIVISION.
PERFORM 100-HOUSEKEEPING.
PERFORM 300-MAINLINE-RTN.
PERFORM 500-CLEANUP.
GOBACK.
100-HOUSEKEEPING.
PERFORM 150-INITIALIZE-FIELDS.
PERFORM 200-OPEN-FILES.
PERFORM 800-READ-RTN.
150-INITIALIZE-FIELDS.
…
200-OPEN-FILES.
…
300-MAINLINE-RTN.
PERFORM 400-PROCESS-RECORD.
PERFORM 700-WRITE-RTN.
PERFORM 800-READ-RTN.
400-PROCESS-RECORD.
…
500-CLEANUP.
PERFORM 900-CLOSE-FILES.
…
700-WRITE-RTN.
…
PERFORM THRU
 One variation on PERFORM is
PERFORM … THRU
 PERFORM … THRU allows you to explicitly
mark & bound the end of the PERFORM chain
with a labeled paragraph
 All of the procedural statements between:
PERFORM <paragraphName>
and THRU <paragraphName>
…are executed
 The best practice is for the exit paragraph to
have one COBOL reserved word in it: EXIT
This returns control to the next sequential
instruction in the perform chain
 Technically, you could PERFORM a COBOL
paragraph THRU any other paragraph.
However, this often leads to complex and
unstructured code
 Difficult to understand and maintain 
 So the convention is to PERFORM THRU a
single paragraph EXIT (as shown) 
53
PROCEDURE DIVISION.
PERFORM 100-HOUSEKEEPING
THRU 100-EXIT.
PERFORM 300-MAINLINE-RTN
THRU 300-EXIT.
PERFORM 500-CLEANUP
THRU 500-EXIT.
GOBACK.
100-HOUSEKEEPING.
PERFORM 150-INITIALIZE-FIELDS
THRU 150-EXIT.
PERFORM 200-OPEN-FILES
THRU 200-EXIT.
PERFORM 800-READ-RTN
THRU 800-EXIT.
100-EXIT.
EXIT.
150-INITIALIZE-FIELDS.
…
150-EXIT.
EXIT.
200-OPEN-FILES.
…
200-EXIT.
EXIT.
…
See Slide Notes
Inline PERFORM
 Another variation on PERFORM is what's
known as an "inline perform"
 An inline PERFORM allows you to encase
COBOL statements and business logic within
a structured statement block – which you can
group or loop through (looping is the next
topic, but Inline PERFORM is often used to
control loops.
PERFORM
<statement>
<statement>
…
PROCEDURE DIVISION.
PERFORM UNTIL END-OF-FILE
IF NOT END-OF-FILE
PERFORM 800-READ-INPUT-FILE
IF NOT END-OF-FILE
MOVE INPUT-REC TO OUTPUT-REC
PERFORM 900-WRITE-RECORD
ELSE
MOVE HIGH-VALUES
TO INPUT-REC
PERFORM 1000-CLOSE-FILES
DISPLAY 'NORMAL EOJ
END-IF
END-IF
END-PERFORM.
…
PERFORM VARYING IDX
FROM 1 BY 1 UNTIL IDX > 100
MOVE REC-IN
TO REC-TABLE(IDX)
END-PERFORM.
END-PERFORM.
 An in-line PERFORM must be delimited by
the END-PERFORM phrase.
54
…
Scope Terminators and Paragraph Names
 You have seen that many of the COBOL
statements can have Scope
Terminators:
END-IF
END-READ
END-COMPUTE
…
100-HOUSEKEEPING.
…
IF ITEM-2 = "AABBCC" OR "AACCDD"
OR "AADDEE"
MOVE ITEM-2 TO ITEM-1
ELSE
MOVE ITEM-3 TO ITEM-1
END-IF
100-EXIT.
This will not compile!
EXIT.
 This is actually a coding best practice
 However, the last statement before the
paragraph (or "exit paragraph") must end
in a period.
55
Type a period after END-IF
100-HOUSEKEEPING.
…
IF ITEM-2 = "AABBCC" OR "AACCDD"
OR "AADDEE"
MOVE ITEM-2 TO ITEM-1
ELSE
MOVE ITEM-3 TO ITEM-1
END-IF.
100-EXIT.
EXIT.
GO TO – Unconditional Transfer of Control
 GO TO branches to the paragraph or section
label after the statement.
 With no automatic, compiler-managed return to
the next sequential instruction
 Ergo all subsequent statements "fall through"
 This can create what is termed "spaghetti
code" – which is typically
 Difficult to read 
 Very difficult to maintain and modify 
 The use of GO TO is universally denounced
in the academic computing world
 And we agree – except for under one very key
and common design pattern (combining GO TO
with PERFORM … THRU) 
 Our "Best Practices" advice:
 Do not use GO TO in COBOL coding, for
transferring control
 EXCEPT under one condition – when you are
using GO TO - for branching to the exit paragraph
in a PERFORM … THRU
 This honors the Perform Chain and execution
will not "fall through"
56
PROCEDURE DIVISION.
PERFORM 100-HOUSEKEEPING
THRU 100-EXIT.
PERFORM 300-MAINLINE-RTN
THRU 300-EXIT.
GOBACK.
100-HOUSEKEEPING.
PERFORM 200-OPEN-FILES
THRU 200-EXIT.
PERFORM 800-READ-RTN
THRU 800-EXIT.
IF END-OF-FILE
DISPLAY "END-OF-JOB"
PERFORM 900-CLOSE FILES
THRU 900-EXIT
GO TO 100-EXIT
ELSE
ADD +1 TO REC-KTR
MOVE ZEROS TO AMOUNT-TOT
END-IF
Perform 300-INIT-FIELDS.
100-EXIT.
EXIT.
…
Transfer of Control Best Practices
 We will cover structured COBOL programming and logic patterns and design
in one of the upcoming units, but for now, consider the following:
Structure your program as a chain of PERFORM THRU paragraphs
Within the paragraphs code anything you need to satisfy your business logic
requirements, including:
 CALLs to external programs – CALL is covered in an upcoming unit
 Nested PERFORM
 Inline PERFORM
 Sequence and conditional logic
 GO TO – BUT ONLY GO TO a PERFORM THRU paragraph EXIT
Try not to use COBOL SECTIONs
 Within COBOL SECTIONs – COBOL paragraphs are considered at the level of
statements – blocks of code where fall through will occur
 The only time you will need a COBOL SECTION is when you're programming is invoking
the COBOL SORT verb (which is tied to INPUT and OUTPUT SORT SECTIONs)
57
Unit
COBOL General Language
Rules
Topics:
 Assignment Statements and Internal Data
Representation
 Math Operations
 Conditional Logic
 Transfer of control
 COBOL Looping Constructs
 Sequential File Processing Patterns
 Java and .NET Equivalents
58
Topic objectives
By the end of this unit you should  Be able to use the PERFORM..TIMES.
 Understand how the PERFORM..UNTIL works and be able to use it to
implement while or do/repeat loops.
 Be able to use PERFORM..VARYING to implement counting iteration
such as that implemented in other languages by the for construct.
59
COBOL Looping Options
 There are three COBOL programming ways to loop:
GO TO <paragraphName> combined with an IF condition that ends the loop:
 Unstructured – creates complex, un-maintainable code
 NOT a best practice – hence will not be covered
PERFORM <paragraphName> n TIMES
 Structured and simple to understand
 But only applicable in cases where the number of loop iterations is known at design time
PERFORM <paragraphName> UNTIL a condition is met
 Structured ("Good")
 Can be used when the number of loop iterations is variable or known
 Net: Use PERFORM <paragraphName> UNTIL for your COBOL looping
requirements.
 When do you need to loop in your COBOL programs?
 Reading/Writing a file until no more records
 Looping through rows returned from a database
 Loading a COBOL internal table
 Processing a COBOL table sequentially
 Calculations
 Algorithms
…in general – you will write few programs that don't loop
60
PERFORM <paragraphName> n
TIMES
 Can PERFORM a paragraph a specified
number of times, in a loop controlled by a:
 Numeric literal
 Numeric integer variable
 Examples:
 Performs all of the COBOL statements between
300-MAINLINE-RTN and 300-EXIT
12 TIMES
 Performs all of the COBOL statements between
310-SUBTOTALS and 310-EXIT the number
of times represented by the integer value in
NBR-REPS
Use PERFORM … n TIMES – when you know
during development how many loop iterations
should be performed at run-time.
61
WORKKING-STORAGE SECTION.
77
NBR-REPS S9(4) COMP.
PROCEDURE DIVISION.
…
PERFORM 300-MAINLINE-RTN
THRU 300-EXIT
12 TIMES.
GOBACK.
300-MAINLINE-RTN.
…
MOVE IN-REC-KTR TO NBR-REPS.
PERFORM 310-SUBTOTALS
THRU 310-EXIT
NBR-REPS TIMES.
…
300-EXIT.
EXIT.
PERFORM UNTIL <condition>
PROCEDURE DIVISION.
PERFORM 100-HOUSEKEEPING
THRU 100-EXIT.
 Structured method of looping when you only
know at run-time how many times the loop
should be iterated over
PERFORM 300-MAINLINE-RTN
THRU 300-EXIT
UNTIL NO-MORE-RECORDS.
 UNTIL
GOBACK.
 Tests a condition for TRUE/FALSE
 If NOT TRUE (repeat – if the condition is
FALSE) PERFORM the specified Paragraph
 If TRUE
– End the loop
– Return program control to the next sequential
instruction following the PERFORM UNTIL
statement
 Additional notes:
 If the UNTIL condition never becomes true?
 Infinite loop 
– If the program is batch, the TIME= parameter on the
JCL will most likely cancel it
– If the program is an online transaction, the operator
will cancel it
– Either way, this is not a good thing 
 There are actually two additional options for
PERFORM UNTIL (next slide)
62
100-HOUSEKEEPING.
OPEN INPUT IN-FILE.
PERFORM 800-READ-RTN
THRU 800-EXIT.
100-EXIT.
EXIT.
300-MAINLINE-RTN.
…
PERFORM 800-READ-RTN.
300-EXIT.
EXIT.
800-READ-RTN.
READ IN-FILE INTO WS-RECORD
AT END MOVE 'Y'
TO SW-NO-MORE-RECORDS.
800-EXIT.
EXIT.
PERFORM UNTIL – With TEST
BEFORE or AFTER
 PERFORM …UNTIL may be modified by
one of two clauses, coded before UNTIL and
after the paragraph name:
1. WITH TEST BEFORE
PROCEDURE DIVISION.
PERFORM 100-HOUSEKEEPING
THRU 100-EXIT.
PERFORM 300-MAINLINE-RTN
THRU 300-EXIT
WITH TEST BEFORE
UNTIL NO-MORE-RECORDS.
 The UNTIL condition is tested before
each PERFORM execution.
 The Paragraphs will be executed 0 or
more times
 Is the default – if this clause is left
unspecified
2. WITH TEST AFTER
 The UNTIL condition is tested after each
PERFORM execution.
 The Paragraphs will be executed 1 or
more times
63
GOBACK.
100-HOUSEKEEPING.
OPEN INPUT IN-FILE.
PERFORM 800-READ-RTN
THRU 800-EXIT.
100-EXIT.
EXIT.
300-MAINLINE-RTN.
…
PERFORM 800-READ-RTN.
300-EXIT.
EXIT.
800-READ-RTN.
READ IN-FILE INTO WS-RECORD
…
800-EXIT.
EXIT.
Lab Assignment
From the course workshop documents, do the following labs:
1. COBOL Looping Lab
64
Unit
COBOL General Language
Rules
Topics:
 Assignment Statements and Internal Data
Representation
 Math Operations
 Conditional Logic
 Transfer of control
 COBOL Looping Constructs
 Sequential File Processing Patterns
 Java and .NET Equivalents
65
Topic objectives
This topic covers basic (simple) sequential file processing – patterns:
 Open files
 Read an initial record from the input file
 Process all records until end-of-input-file




Edit and validate data
Compute totals, subtotals and accumulators
Write output records
Read the next input file record
 Close files and end the job

In subsequent topics of this course, we will dive much more deeply into
file handling, as a majority of COBOL batch processing depends on
concepts and coding patterns that are variations of the above
 We will also touch on the basic batch program design patterns you will
want to use going forward in this course and later in your production
COBOL work
By the end of this chapter you will be able to:
 OPEN, READ, WRITE and CLOSE files
 Loop through and input file, processing all of the records until completed
66
Sequential File Processing
Sequential File Processing consists of a well-documented set of processing –
or a pattern that you will see in many program requirements
 You read one or more input files until:


Your business logic requirements are fulfilled
End-of-File
 While reading files you typically:




Edit or evaluate data
Add numeric values to total and sub-total fields – perform business calculations
Assign (MOVE) values
WRITE output record(s) – either to an output file, report or both
 You must be cognizant of:



Bad or invalid data (and know what to do about it when it shows up in your fields)
Empty input files
READ/WRITE I/O errors that may occur
 After reaching end-of-file you will typically:
WRITE a final output record, with summary computed values
CLOSE all files
DISPLAY a successful end-of-job message
Input File
Note - more
than likely
NOT a tape
Device 
COBOL Program
Business Logic
67
Record Buffer



Record Buffer

Output Report
Output File
Sequential File Processing Pattern – Simple Batch Design Pattern
This first batch application pattern "Process One Input File" – consists of
the following pattern
 Perform an initialization routine
 Initialize values in Working-Storage
 OPEN the files – for either input or output
 PERFORM a "priming" input-record read – an initial read statement that
simplifies:
 Empty input-file-processing problems
 Reading past end-of-file logic problems
 Perform a process-the-file routine, until end-of-input-file





Validate the data – using the conditional logic statements learned in this unit
Move the data – using the assignment statements learned in this unit
Do computations, calculations, etc. – using the COBOL math statements
Write the record
Read the next input record
 Perform an end-of-job routine
 Complete final computations
 WRITE final output record with final computations
 CLOSE all files and display an end-of-job message on the Console
68
File I/O Review – OPEN
…
ENVIRONMENT DIVISION.
External
Device
INPUT-OUTPUT SECTION.
External File
SELECT INTFILENAME ASSIGN TO …
…
DATA DIVISION.
FILE SECTION
Record Buffer
FD
INTFILENAME…
01
OUT-REC.
…
Recall the following:
PROCEDURE DIVISION.
 SELECT/ASSIGN connects your
…
internal (logical) filename with
OPEN
INPUT FILE1, FILE2
OUTPUT FILE3, FILE4.
external (physical) file-spec
 FILE SECTION is required for each
SELECT/ASSIGN file
 OPEN references the logical
(internal) filename
 Can OPEN multiple files with one
statement (as shown)
…
 Note carefully the syntax for OPEN
 See Slide Notes, for
additional learning content
69
File I/O Review – READ INTO
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
SELECT INTFILENAME ASSIGN TO …
DATA DIVISION.
FILE SECTION
FD INTFILENAME …
Record Buffer
01 IN-REC.
WORKING-STORAGE SECTION
01 IN-REC-WS.
01 END-OF-FILE-FLAG PIC X.
PROCEDURE DIVISION.
OPEN INPUT INTFILENAME.
READ INTFILENAME INTO IN-REC
AT END MOVE ‘Y’ to END-OF-FILE-FLAG.
…
External
Device
External File
F
I
L
E
R
E
A
D

 See Slide Notes,
Recall the following:
 File must be OPEN before you try to READ from it
 READ retrieves each record from an external file:
- Into the record specified in your FILE SECTION
for additional
learning content
* Note that the DATA DIVISION's FILE SECTION is sometimes referred to as an I/O "buffer"
- Into WORKING-STORAGE - if you've coded READ INTO
 AT END condition occurs after the last record is READ from the file
- If you attempt to read past end-of-file your program will ABEND
70
File I/O Review – WRITE FROM
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
SELECT OUTFILENAME ASSIGN TO …
DATA DIVISION.
FILE SECTION
FD
OUTFILENAME…
Record Buffer
01
OUT-REC.
WORKING-STORAGE SECTION
01 OUT-REC-WS.
PROCEDURE DIVISION.
OPEN OUTPUT OUTFILENAME.
External
Device
External File
W
R
I
T
E
O
P
E
R
A
T
I
O
N
WRITE OUT-REC
FROM OUT-REC-WS.
…
 See Slide Notes,
Recall the following:
 File must be OPEN before you try to WRITE a record to it
- An ABEND condition occurs, if try to write to an un-opened file
 WRITE creates a new record at the end of a sequential/external file:
- From the record specified in your FILE SECTION
- From WORKING-STORAGE - if you've coded WRITE FROM
 Close opened output files before your program ends
71
for additional
learning content
File I/O Review – CLOSE
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
SELECT INTFILENAME ASSIGN TO …
…
DATA DIVISION.
FILE SECTION
Record Buffer
FD
INTFILENAME…
01
OUT-REC.
…
PROCEDURE DIVISION.
Recall
…
F
I
L
E
External
Device
External File
C
L
O
S
E
the following:
CLOSE
FILE1, FILE2,
FILE3, FILE4.
 CLOSE every opened file
…
 Can CLOSE multiple files with one
statement (as shown)
 Can re-OPEN a file after closing
- Input file
- Output file
 Note carefully the syntax for
CLOSE
 See Slide Notes, for additional learning content
72
Sequential File Processing Pattern –
Pseudo-Code
 In a subsequent unit of this course we will
cover the concept of design and programming
patterns with COBOL
 For now, here is your first simple, sequential
file-handling pattern, in pseudo-code.
 Study the control-flow to understand the
paragraph PERFORM process, and purpose
of each statement block
 Tie this back to the code you the previous
slide in this unit.
 What is not part of this processing pattern are
the actual details of the:
 Data Validation
 Calculations and computations
… which can be extremely complex and will most
likely take up the majority percentage of your
coding cycles.
 There are other algorithms that can do the
same sequential process, but we feel this is a
simple, easy-to-read/maintain/debugsupport/and extend approach
73
PROCEDURE DIVISION.
Do Init-Routine
Do Process-Files
until No-More-Data
Do End-of-Job-Routine
GOBACK.
Init-Routine.
Open files
READ Input-File
Process-Files.
Validate input data
Perform calculations and
sub-totals
Move data to output Record
Write Output-Record
READ Input-File
End-of-Job-Routine.
Final computations
Move Data to output Record
Write output record
Close Files
Putting it All Together - A Complete Example of a Sequential File
Processing Program
 Read through (study) the code in this sample
small sequential file processing program.
 Trace the concepts, COBOL syntax and
statement semantics learned in this, and
the previous Unit to the actual code in this
program.
 Feel free to refer-back to your slides, the
course supplemental text or your notes – if
necessary
Select External File
Assign to COBOL
(internal) file name
FILE SECTION FDs
Matching the SELECT/ASSIGN
Clauses for each external file
Note – this example continues over the next three slides
74
A Complete Example of a Sequential File Processing Program
– WORKING-STORAGE SECTION
File Status fields
Automatically updated
By COBOL and the O.S.
A final-totals output record
Input and Output records
You will often see these
coded in WORKINGSTORAGE because they
are easier to find in a
System log file (called a
DUMP file) if your
program files (ABENDS)
when executing on the
mainframe
Holding fields for intermediate
result calculations and values
75
A Complete Example of a Sequential File Processing Program – PROCEDURE DIVISION
E
D
I
T
S
Processing
• Calculations
• Computations
Our Sequential File Pattern – in COBOL
M
O
V
E
Read the code line-by-line (as if you were debugging it –
In other words, if there's a PERFORM – jump down to the
Performed paragraph. When finished jump back, etc.)
Note the use of:
• PERFORM THRU
• AT END/GO TO "EXIT"
• PERFORM UNTIL
• For each record in the input file, do 100-MAINLINE
Write the current record
Read the next record in the file
76
A Complete Example of a Sequential File Processing Program
– No More Records in the File
 When there are no more
records left to process
 Do final calculations
 Move the fields to final output record
 WRITE
 CLOSE all files
 Display a message on the console
77
Lab Assignment
From the course workshop documents, do the following labs:
1. Process Input File1
2. Process InputFile2
78
Unit
COBOL General Language
Rules
Topics:
 Assignment Statements and Internal Data
Representation
 Math Operations
 Conditional Logic
 Transfer of control
 COBOL Looping Constructs
 Reading and Writing Files - Review
 Java and .NET Equivalents
79
Java .NET COBOL Equivalents
COBOL
JAVA
VB.NET
MOVE (elementary field)
Java variable assignment (right to left)
Variable assignment (right to left)
MOVE (group field move)
Java OBJECT assignment (right to left)
Variable assignment (right to left)
MOVE CORRESPONDING
N/A
N/A
MOVE with OF qualifier
Qualified assignment var1.var2.var3
Qualified assignment var1.var2.var3
ADD
Standard math computation (no separate statement)
Standard math computation (no separate statement)
SUBTRACT
"
"
MULTIPLY
"
"
DIVIDE
"
"
COMPUTE
"
"
IF/ELSE AND/OR
If
If
EVALUATE
case
case
PERFORM
Method invocation
Method invocation
PERFORM THRU
While or FOR – method invocation
While or FOR – method invocation
COBOL Paragraphs and Sections
Java Labels
Label
GO TO
Break/Continue can refer to a Label (same behavior as GO TO EXIT)
Break/Continue can refer to a Label (same behavior as GO TO EXIT)
PERFORM THRU UNTIL
While or FOR – method invocation
While or FOR – method invocation
OPEN
//comment, as Java opens files automatically
OPEN()
CLOSE
DataInputStream.close()
CLOSE()
WRITE
DataInputStream/BufferedInputStream/FileInputStream
StreamWriter/BinaryWriter
READ
DataInputStream/BufferedInputStream/FileInputStream
StreamReader/BinaryReader
ACCEPT
Java.util.Scannner (System.in)
Console.Read
DISPLAY
System.out.println
Console.WriteLine – or Console.Write
80
Descargar

Slide 1