Cobol 5i4l6f

Structured COBOL Programming 10th edition

John Wiley & Sons, Inc.

Nancy Stern Hofstra University

Robert A. Stern Nassau Community College

James P. Ley University of Wisconsin-Stout PowerPoint Presentation

Winifred J. Rex Bowling Green State University

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Chapter 7

Computing in COBOL: The Arithmetic Verbs and Intrinsic Functions

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Chapter Objectives To familiarize you with • Ways in which arithmetic may be performed in COBOL • Formats and options available with arithmetic verbs

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Chapter Contents • • • •

Basic Arithmetic Verbs Options Available with Arithmetic Verbs COMPUTE Statement Signed Numbers in Arithmetic Operations • Intrinsic Functions

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Basic Arithmetic Verbs • ADD, SUBTRACT, MULTIPLY, DIVIDE • All require fields operated on to – Have numeric PICTURE clauses – Contain numeric data when statements executed

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ADD … TO Statement Format 1

identifier-1 ADD

… TO identifier-2 ...

literal-1 • identifier-1 or literal-1 added to identifier-2 • Result stored in identifier-2

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ADD … TO Examples Assume X, Y and Z are numeric fields X = 5, Y = 3 and Z = 7 ADD Statement Add X To Y Add X, 9 To Y Add X, 6, Y To Z

Result Y=8 Y = 17 Z = 21

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ADD … TO Statement • Identifiers preceding TO are unchanged • Value of identifier after TO – Used in ADD operation – Original value replaced with ADD result

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ADD … GIVING Statement Format 2

identifier-1 ADD

… GIVING identifier-2 ...

literal-1

• Identifiers and literals preceding GIVING added together • Result stored in identifier-2

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ADD … GIVING Examples Assume X, Y and Z are numeric fields X = 5, Y = 3 and Z = 7 ADD Statement Add X, Y Giving Z Add X, 10 Giving Y Add X, 4, Y Giving Z

Result Z=8 Y = 15 Z = 12

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ADD … GIVING Statement • Identifiers preceding GIVING are unchanged • Value of identifier after GIVING – Not part of ADD operation – Original value replaced with ADD result – May be report-item with edit symbols

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ADD … GIVING Statement • TO may be included before last identifier or literal preceding GIVING • For example: Add X, 4 To Y Giving Z – Adds values of X, 4 and Y together – Stores result in Z

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ADD Statement • Comma followed by one space may be used to separate operands • Result of ADD always placed in field(s) after TO or GIVING • Result field must be data-name, not a literal

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Producing More Than One Sum • Several ADD operations can be done in single statement • Assume X, Y and Z are numeric fields X = 5, Y = 3 and Z = 7 ADD Statement Add X To Y, Z Add X, 6 Giving Y, Z

Result Y = 8, Z = 12 Y = 11, Z = 11 7-14

ADD … TO vs ADD … GIVING • Use ADD … TO when original contents of result operand – Need to be included in operation – But are not needed after operation

• Use ADD … GIVING when – Original contents of all operands except result field are to be retained

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SUBTRACT Statement Format 1

identifier-1 SUBTRACT

… FROM identifier-2 ...

literal-1

• identifier-1 or literal-1 subtracted from identifier-2 • Result stored in identifier-2

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SUBTRACT Examples Assume A, B and C are numeric fields A = 6, B = 2 and C = 18 SUBTRACT Statement Subtract A From C Subtract B, 5 From C Subtract B From A, C

Result C = 12 C = 11 A = 4, C = 16

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SUBTRACT Statement Rules • All identifiers and literals must be numeric • Data-name, not a literal, must follow FROM • All fields, literals preceding FROM added together • Sum subtracted from field after FROM • Result stored in field after FROM 7-18

SUBTRACT … GIVING Statement Format 2

identifier-1 SUBTRACT

… FROM

literal-1

identifier-2 literal-2

GIVING identifier-3 ...

• identifier-1 or literal-1 subtracted from identifier-2 or literal-2 • Result stored in identifier-3 7-19

SUBTRACT … GIVING Examples Assume A, B and C are numeric fields A = 6, B = 2 and C = 18 SUBTRACT Statement Subtract B From A Giving C Subtract A From 15 Giving C Subtract A, 4 From C Giving B

Result C=4 C=9 B=8

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SUBTRACT … GIVING Rules • All identifiers, literals before FROM must be numeric • GIVING must be followed by data-name – May be numeric or report-item

• All fields, literals preceding FROM added together • Sum subtracted from field after FROM • Result stored in field after GIVING 7-21

MULTIPLY Statement Format 1

MULTIPLY

BY identifier-2 ... literal-1

identifier-1

• identifier-1 or literal-1 multiplied by identifier-2 identifier-1

• Result stored in identifier-2 7-22

MULTIPLY Examples Assume Q, R and S are numeric fields Q = 4, R = 7 and S = 5 MULTIPLY Statement

Multiply Q By R Multiply 10 By S Multiply 2 By R, S

Result R = 28 S = 50 R = 14, S = 10

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MULTIPLY … GIVING Statement Format 2

identifier-1

MULTIPLY

identifier-2 BY

literal-1

literal-2

GIVING identifier-3 ...

• identifier-1 or literal-1 multiplied by identifier-2 or literal-2 • Result stored in identifier-3 7-24

MULTIPLY … GIVING Examples Assume Q, R and S are numeric fields Q = 4, R = 7 and S = 5 MULTIPLY Statement Multiply Q By R Giving S Multiply Q By 3 Giving S Multiply 6 By Q Giving R, S

Result S = 28 S = 12 R = 24 S = 24 7-25

MULTIPLY Statement • Only two operands can be multiplied • To obtain product of 3 operands requires two instructions To find Price x Qty x Discount

Multiply Price By Qty Giving WS-Amt Multiply Discount By WS-Amt 7-26

DIVIDE Statement Format 1

identifier-1

DIVIDE

INTO identifier-2 ... literal-1

• identifier-1 or literal-1 divided into identifier-2 • Result stored in identifier-2

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DIVIDE Examples Assume X, Y and Z are numeric fields X = 2, Y = 12 and Z = 8 DIVIDE Statement Divide X Into Y Divide 3 Into Y Divide 2 Into Y, Z

Result Y=6 Y=4 Y = 6, Z = 4

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DIVIDE … GIVING Statement Format 2

DIVIDE

identifier-1 literal-1

INTO BY

identifier-2 literal-2

GIVING identifier-3 ...

• identifier-1 or literal-1 divided into or by identifier-2 or literal-2 • Result stored in identifier-3 7-29

DIVIDE … GIVING Examples Assume X, Y and Z are numeric fields X = 2, Y = 12 and Z = 8 DIVIDE Statement Divide X Into Y Giving Z Divide Y By X Giving Z Divide 16 By Z Giving X, Y

Result Z=6 Z=6 X=2 Y=2 7-30

REMAINDER Clause • Optional clause with DIVIDE used to store remainder of division • Assume Q and R have PICTUREs of 99

Divide 70 By 15 Giving Q Remainder R • Stores quotient 4 in Q and integer remainder 10 in R 7-31

ROUNDED Option • Arithmetic result truncated if room to store all decimal positions not available – Result of 3.89 stored in field with PIC 9V9 as 3^8

• Include ROUNDED to round result to PICTURE specification – Result of 3.89 stored as 3.9 if ROUNDED option used 7-32

ROUNDED Option Examples

01 Amt1 01 Amt2

Pic 9V99 Pic 999.

Value 2.25.

Arithmetic statement Multiply .3 By Amt1 Multiply .3 By Amt1 Rounded Divide 150 By 9 Giving Amt2 Rounded

Result .675 .675

Value Stored Amt1 = 0^67 Amt1 = 0^68

16.66… Amt2 = 017 7-33

Overflow or Size Error • Occurs when result value too large to be stored in result field • Result of this ADD statement is 1,075 Add 350 To 725 Giving Num • If Num has PICTURE of 999, only 3 digits can be stored • High-order digits truncated so 075 stored in Num 7-34

Checking for Overflow • Any arithmetic statement may include one or both size error clauses • ON SIZE ERROR statement(s) – Specifies one or more statements to be executed if overflow (size error) occurs

• NOT ON SIZE ERROR statement(s) – Specifies one or more statements to be executed if overflow (size error) does not occur 7-35

SIZE ERROR Clause Example Add X To Y Giving Z On Size Error Display ' Result too large' Not On Size Error Perform Calc-Para End-Add • If sum of X and Y too large to store in Z, Display statement executed • If Z large enough for result, Calc-Para is performed 7-36

SIZE ERROR Clauses • When using one or both clauses, use scope terminator to end arithmetic operation – END-ADD, END-SUBTRACT – END-MULTIPLY, END-DIVIDE

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Size of Receiving Fields • Ensure receiving field has PICTURE large enough to store result • Addition - define resultant field one position larger than largest field added • Subtraction - define resultant field as large as number being subtracted from – Assumes positive numbers – Assumes smaller subtracted from larger number 7-38

Size of Receiving Fields • Multiplication - define resultant field equal to sum of lengths of operands begin multiplied • Division - define resultant field equal to sum of number of digits in divisor and dividend

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COMPUTE Statement • General arithmetic statement using symbols in place of arithmetic verbs Symbol Verb + ADD SUBTRACT * MULTIPLY / DIVIDE ** exponentiation 7-40

COMPUTE Statement Format

COMPUTE identifier-1 … =

arithmetic-exp-1 literal-1 identifier-2

• Identifier to left of equal sign set to value of arithmetic-expression, literal or identifier on right of equal sign 7-41

COMPUTE Examples Assume X, Y and Z are numeric fields X = 9, Y = 4 and Z = 12 COMPUTE Statement Compute Z = X * Y Compute X = Z - Y + 2 Compute X = Y Compute Z = Y ** 2

Result Z = 36 X = 10 X=4 Z = 16 7-42

Order of Evaluation • Arithmetic expression may include any combination of symbols +, -, *, / or ** • Order of operations 1. 2. 3. 4.

** * or / + or ()

all exponentiation performed first in order or appearance left to right in order or appearance left to right override rules 1-3, all operations in ( ) performed first

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COMPUTE Examples Assume X, Y and Z are numeric fields X = 6, Y = 18 and Z = 5 COMPUTE Statement Compute Z = Y / X + 3 Compute Z = Y / (X + 3) Compute Y = Z + X * 10 Compute Y = Z * X / 10

Result Z=6 Z=2 Y = 65 Y=3 7-44

COMPUTE Statement • COMPUTE can include same optional clauses used with other arithmetic verbs • ROUNDED follows result field (identifier preceding equal sign) • If ON SIZE ERROR or NOT ON SIZE ERROR clauses used, include scope terminator END-COMPUTE 7-45

Signed Numbers • Use S in PIC clause of result field if – Numbers used in calculation may be negative – Calculation may produce negative results

• PIC clause without S assumed to be unsigned – If negative result stored in unsigned field, sign not retained 7-46

Intrinsic Functions • Built-in procedures to perform particular task like – Find square root of number – Convert letters to uppercase – Get current date

• Approved as extensions to COBOL standard in 1989 • Now included in many compilers 7-47

Intrinsic Functions Example

Find square root of X and place result in Y Compute Y = Function Sqrt(X) • Value of X ed to function called Sqrt • Code in function finds square root of X • Result returned by Sqrt assigned to Y 7-48

Intrinsic Functions Example

Convert More-Data to uppercase Move Function Upper-Case(More-Data) To Up-More-Data • If More-Data = "Yes", function UpperCase returns value "YES" • Value "YES" moved to Up-More-Data 7-49

Intrinsic Functions Format

FUNCTION function-name (argument)

• Argument - input to function – May be numeric or alpha-numeric depending on function – Functions may have 0, 1 or more

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Intrinsic Functions • Output of function - result returned after function performs its task • Function returning alphanumeric result used in statements using alphanumeric data-items • Function returning numeric result can be used only in arithmetic expressions 7-51

COBOL 2002+ Changes • Spaces around arithmetic operators will no longer be required • COMPUTE statement will yield same results on all compilers – Will make precision or number of decimal places in each intermediate calculation fixed

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Chapter Summary • ADD, SUBTRACT, MULTIPLY, and DIVIDE verbs – format without GIVING • Receiving field is part of arithmetic • May not be report-item

– with GIVING format • Receiving field is not part of arithmetic • May be report-item

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Chapter Summary • COMPUTE used for any combination of arithmetic operations • Order of evaluation of operators 1. 2. 3. 4.

** * or / in sequence left to right + or - in sequence left to right ( ) override normal hierarchy rules

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Chapter Summary • ROUNDED can follow receiving field in any arithmetic verb • ON SIZE ERROR, NOT ON SIZE ERROR – Can be used with any arithmetic verb – Include scope terminator (e.g., END-ADD)

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Chapter Summary • Intrinsic functions added as COBOL extensions in 1989 – Calendar – Numerical analysis – Statistical – Trigonometric – Financial – Character and String 7-56

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