Chapter 7 Computing in COBOL The Arithmetic Verbs

Chapter 7 Computing in COBOL: The Arithmetic Verbs and Intrinsic Functions 71

Chapter Contents Basic Arithmetic Verbs Options Available with Arithmetic Verbs COMPUTE Statement Signed Numbers in Arithmetic Operations Intrinsic Functions 72

Basic Arithmetic Verbs ADD, SUBTRACT, MULTIPLY, DIVIDE All require fields operated on to ◦ Have numeric PICTURE clauses ◦ Contain numeric data when statements executed 73

ADD … TO Statement Format 1 ADD identifier-1 literal-1 … TO identifier-2. . . identifier-1 or literal-1 added to identifier-2 Result stored in identifier-2 74

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 Identifiers preceding TO are unchanged Value of identifier after TO ◦ Used in ADD operation ◦ Original value replaced with ADD result 75

ADD … GIVING Statement Format 2 ADD identifier-1 literal-1 … GIVING identifier-2. . . Identifiers and literals preceding GIVING added together Result stored in identifier-2 76

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 Identifiers preceding GIVING are unchanged Value of identifier after GIVING ◦ Original value replaced with ADD result ◦ May be report-item with edit symbols 77

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 78

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 ◦ ADD HOURS-WORKED TO WEEKLY-HOURS ◦ Vs. Giving 79

SUBTRACT Statement Format 1 SUBTRACT identifier-1 literal-1 … FROM identifier-2. . . identifier-1 or literal-1 subtracted from identifier-2 Result stored in identifier-2 710

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 = 16 711

SUBTRACT … GIVING Statement Format 2 SUBTRACT identifier-1 … 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-3 712

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=8 713

MULTIPLY Statement Format 1 MULTIPLY identifier-1 literal-1 BY identifier-2. . . identifier-1 or literal-1 multiplied by identifier-2 Result stored in identifier-2 714

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 = 10 715

MULTIPLY … GIVING Statement Format 2 MULTIPLY identifier-1 literal-1 BY identifier-2 literal-2 GIVING identifier-3. . . identifier-1 or literal-1 multiplied by identifier-2 or literal-2 Result stored in identifier-3 716

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 = 24 717

MULTIPLY Statement Only two operands can be multiplied using the MULTIPLY statement 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 718

DIVIDE Statement Format 1 DIVIDE identifier-1 literal-1 INTO identifier-2. . . identifier-1 or literal-1 divided into identifier-2 Result stored in identifier-2 719

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 = 4 720

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-3 721

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 X=2 Y=2 722

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 What can this be used for? ? ? Same as MOD 723

ROUNDED Option Arithmetic result truncated if room to store all decimal positions not available ◦ Result of 3. 89 stored in field with PIC 9 V 9 as 3^8 Include ROUNDED to round result to PICTURE specification ◦ Result of 3. 89 stored as 3. 9 if ROUNDED option used ◦ Its actually adding. 5 then truncating 724

ROUNDED Option Examples 01 01 Amt 1 Pic 9 V 99 Value 2. 25. Amt 2 Pic 999. Arithmetic statement Multiply. 3 By Amt 1 Rounded Divide 150 By 9 Giving Amt 2 Rounded Result. 675 Value Stored Amt 1 = 0^67 Amt 1 = 0^68 16. 66… Amt 2 = 017 725

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 726

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 727

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 When using one or both clauses, use scope terminator to end arithmetic operation ◦ END-ADD, END-SUBTRACT ◦ END-MULTIPLY, END-DIVIDE 728

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 729

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 730

COMPUTE Statement General arithmetic statement using symbols in place of arithmetic verbs Symbol Verb + ADD SUBTRACT * MULTIPLY / DIVIDE ** exponentiation 731

COMPUTE Statement Format arithmetic-exp-1 COMPUTE identifier-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 732

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 = 16 733

Order of Evaluation Arithmetic expression may include any combination of symbols +, -, *, / or ** Order of operations 1. ( ) override rules 1 -3, all operations in ( ) performed first 2. ** all exponentiation performed first 3. * or / in order or appearance left to right 4. + or - in order or appearance left to right Same rules apply here as standard math 734

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=3 735

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 ENDCOMPUTE 736

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 We discussed this already 737

Intrinsic Functions Built-in procedures to perform particular task like ◦ Find square root of number ◦ Convert letters to uppercase ◦ Get current date Looks like our compiler handles these because of Lab 2 with the NUMVAL function 738

Intrinsic Functions Example Find square root of X and place result in Y Compute Y = Function Sqrt(X) Value of X passed to function called Sqrt Code in function finds square root of X Result returned by Sqrt assigned to Y 739

Intrinsic Functions Example Convert More-Data to uppercase Move Function Upper-Case (More-Data) To Up-More-Data If More-Data = "Yes", function Upper-Case returns value "YES" Value "YES" moved to Up-More-Data 740

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, of course Page 283 – 288 has a list of several categorized by type 741

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 742

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 743

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) 744

Chapter Summary Intrinsic functions added as COBOL extensions in 1989 ◦ ◦ ◦ Calendar Numerical analysis Statistical Trigonometric Financial Character and String 745