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Computing in COBOL: The Arithmetic Verbs and Intrinsic Functions

Chapter 7. Computing in COBOL: The Arithmetic Verbs and Intrinsic Functions. Chapter Contents. Basic Arithmetic Verbs Options Available with Arithmetic Verbs COMPUTE Statement Signed Numbers in Arithmetic Operations Intrinsic Functions. Basic Arithmetic Verbs.

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Computing in COBOL: The Arithmetic Verbs and Intrinsic Functions

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

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

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

  4. 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

  5. ADD … TO Examples Assume X, Y and Z are numeric fields X = 5, Y = 3 and Z = 7 ADD StatementResult Add X To Y Y = 8 Add X, 9 To Y Y = 17 Add X, 6, Y To Z Z = 21 • Identifiers preceding TO are unchanged • Value of identifier after TO • Used in ADD operation • Original value replaced with ADD result

  6. 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

  7. ADD … GIVING Examples Assume X, Y and Z are numeric fields X = 5, Y = 3 and Z = 7 ADD StatementResult Add X, Y Giving Z Z = 8 Add X, 10 Giving Y Y = 15 Add X, 4, Y Giving Z 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

  8. 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 StatementResult Add X To Y, Z Y = 8, Z = 12 Add X, 6 Giving Y, Z Y = 11, Z = 11

  9. 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

  10. 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

  11. SUBTRACT Examples Assume A, B and C are numeric fields A = 6, B = 2 and C = 18 SUBTRACT StatementResult Subtract A From C C = 12 Subtract B, 5 From C C = 11 Subtract B From A, C A = 4, C = 16

  12. SUBTRACT … GIVING Statement Format 2 identifier-1 identifier-2 SUBTRACT … FROM literal-1 literal-2 GIVING identifier-3 ... • identifier-1 or literal-1 subtracted from identifier-2 or literal-2 • Result stored in identifier-3

  13. SUBTRACT … GIVING Examples Assume A, B and C are numeric fields A = 6, B = 2 and C = 18 SUBTRACT StatementResult Subtract B From A Giving C C = 4 Subtract A From 15 Giving C C = 9 Subtract A, 4 From C Giving B B = 8

  14. MULTIPLY Statement Format 1 identifier-1 MULTIPLYBY identifier-2 ... literal-1 • identifier-1 or literal-1 multiplied by identifier-2 • Result stored in identifier-2

  15. MULTIPLY Examples Assume Q, R and S are numeric fields Q = 4, R = 7 and S = 5 MULTIPLY StatementResult Multiply Q By R R = 28 Multiply 10 By S S = 50 Multiply 2 By R, S R = 14, S = 10

  16. MULTIPLY … GIVING Statement identifier-1 identifier-2 MULTIPLYBY literal-1 literal-2 GIVING identifier-3 ... • identifier-1 or literal-1 multiplied by identifier-2 or literal-2 • Result stored in identifier-3 Format 2

  17. MULTIPLY … GIVING Examples Assume Q, R and S are numeric fields Q = 4, R = 7 and S = 5 MULTIPLYStatementResult Multiply Q By R Giving S S = 28 Multiply Q By 3 Giving S S = 12 Multiply 6 By Q Giving R, S R = 24 S = 24

  18. 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

  19. DIVIDE Statement Format 1 identifier-1 DIVIDEINTO identifier-2 ... literal-1 • identifier-1 or literal-1 divided into identifier-2 • Result stored in identifier-2

  20. DIVIDE Examples Assume X, Y and Z are numeric fields X = 2, Y = 12 and Z = 8 DIVIDEStatementResult Divide X Into Y Y = 6 Divide 3 Into Y Y = 4 Divide 2 Into Y, Z Y = 6, Z = 4

  21. DIVIDE … GIVING Statement Format 2 identifier-1 INTO identifier-2 DIVIDE literal-1 BY literal-2 GIVING identifier-3 ... • identifier-1 or literal-1 divided into or by identifier-2 or literal-2 • Result stored in identifier-3

  22. DIVIDE … GIVING Examples Assume X, Y and Z are numeric fields X = 2, Y = 12 and Z = 8 DIVIDEStatementResult Divide X Into Y Giving Z Z = 6 Divide Y By X Giving Z Z = 6 Divide 16 By Z Giving X, Y X = 2 Y = 2

  23. 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

  24. 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 • Its actually adding .5 then truncating

  25. ROUNDED Option Examples 01 Amt1 Pic 9V99 Value 2.25. 01 Amt2 Pic 999. Arithmetic statementResult Value Stored Multiply .3 By Amt1 .675 Amt1 = 0^67 Multiply .3 By Amt1 Rounded .675 Amt1 = 0^68 Divide 150 By 9Giving Amt2 Rounded 16.66… Amt2 = 017

  26. 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

  27. Checking for Overflow • Any arithmetic statement may include one or both size error clauses • ON SIZEERROR statement(s) • Specifies one or more statements to be executed if overflow (size error) occurs • NOT ON SIZEERROR statement(s) • Specifies one or more statements to be executed if overflow (size error) does not occur

  28. 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

  29. 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

  30. 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

  31. COMPUTE Statement • General arithmetic statement using symbols in place of arithmetic verbs SymbolVerb + ADD - SUBTRACT * MULTIPLY / DIVIDE ** exponentiation

  32. COMPUTE Statement arithmetic-exp-1 COMPUTEidentifier-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 Format

  33. COMPUTE Examples Assume X, Y and Z are numeric fields X = 9, Y = 4 and Z = 12 COMPUTE StatementResult Compute Z = X * Y Z = 36 Compute X = Z - Y + 2 X = 10 Compute X = Y X = 4 Compute Z = Y ** 2 Z = 16

  34. 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

  35. COMPUTE Examples Assume X, Y and Z are numeric fields X = 6, Y = 18 and Z = 5 COMPUTE StatementResult Compute Z = Y / X + 3 Z = 6 Compute Z = Y / (X + 3) Z = 2 Compute Y = Z + X * 10 Y = 65 Compute Y = Z * X / 10 Y = 3

  36. 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

  37. 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

  38. 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

  39. 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

  40. 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

  41. 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

  42. 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

  43. Chapter Summary • COMPUTE used for any combination of arithmetic operations • Order of evaluation of operators 1. ** 2. * or / in sequence left to right 3. + or - in sequence left to right 4. ( ) override normal hierarchy rules

  44. 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)

  45. Chapter Summary • Intrinsic functions added as COBOL extensions in 1989 • Calendar • Numerical analysis • Statistical • Trigonometric • Financial • Character and String

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