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COBOL (COMMON BUSINESS ORIENTED LANGUAGE)

COBOL (COMMON BUSINESS ORIENTED LANGUAGE). Chapter-1. Text Books. M.K.Roy and D. Ghosh Dastidar , COBOL Programming , Tata McGraw Hill , 2001, COBOL—85,2 nd Edition. Nancy Stern and Robert A Stern , 8 th edition, Structured COBOL Programming , John Wiley & Sons , 1998. Contents.

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COBOL (COMMON BUSINESS ORIENTED LANGUAGE)

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  1. COBOL (COMMON BUSINESS ORIENTED LANGUAGE) Chapter-1

  2. Text Books • M.K.Roy and D. Ghosh Dastidar, COBOL Programming, Tata McGraw Hill, 2001, COBOL—85,2nd Edition. • Nancy Stern and Robert A Stern, 8th edition, Structured COBOL Programming, John Wiley & Sons, 1998.

  3. Contents • History of COBOL • Features & Language Fundamentals • Program Structure • Coding Format for COBOL Programs • Character Set, Words, Data Names, Literals.

  4. Nature of COBOL • popular Business-oriented language • Standard language • English-like language • Relatively easy to understand

  5. History of COBOL • 1959 – United States Department of Defense • 1960 - COBOL initial specifications presented by CODASYL (Conference on Data Systems Languages) • 1964 – BASIC COBOL extended to Visual COBOL • 1968 – ANSI (American National Standards Institute) developed American National Standard (ANS) COBOL • 1974 – ANSI published revised version of (ANS) COBOL – Business applications needed to manipulate character as well as numeric data – String operations added • 1985 – COBOL 85 Standards was introduced with revised version of COBOL-74.

  6. COBOL • What does COBOL stand for? COmmon Business Oriented Language. • Which are target area of COBOL applications? Defense, Aircraft, Insurance, Finance, Retail etc (file & data oriented applications involved) • So we can say that COBOL is basically used for writing business applications and not for developing system software

  7. COBOL – Program Structure PROGRAM Principal portions of a program. There are 4 divisions – • Identification (Required) • Environment (Optional) • Data (Optional) • Procedure (Required) DIVISIONS User defined chunk of code which consists of one/more paragraphs. e.g. a) U000-CHECK-LOG SECTION. b) FILE SECTION. SECTIONS User defined chunk of code which consists of one/more sentences. e.g. a) P000-PRINT-FINAL-TOTALS. b) PROGRAM-ID. PARAGRAPHS A SENTENCE consists of one or more statements and is terminated by a full stop. e.g. a) MOVE .21 TO VAT-RATEb) COMPUTE VAT-AMOUNT = PRODUCT-COST * VAT-RATE. A STATEMENT consists of a COBOL verb and an operand or operands. e.g. SUBTRACT T-TAX FROM GROSS-PAY GIVING NET-PAY SENTENCES RESERVED WORDS CHARACTERS STATEMENTS USER DEFINED WORDS

  8. Example IDENTIFICATION DIVISION. PROGRAM-ID. Multiplier. DATA DIVISION. WORKING-STORAGE SECTION. 01 Num1 PIC 9 VALUE ZEROS. 01 Num2 PIC 9 VALUE ZEROS. 01 Result PIC 99 VALUE ZEROS. PROCEDURE DIVISION. DISPLAY "Enter first number (1 digit) : " . ACCEPT Num1. DISPLAY "Enter second number (1 digit) : “. ACCEPT Num2. MULTIPLY Num1 BY Num2 GIVING Result. DISPLAY "Result is = ", Result. STOP RUN.

  9. COBOL CHARACTER SET Overview

  10. COBOL coding sheet

  11. COBOL coding rules • Each line is considered to be made up of 80 columns. • Columns 1 to 6 are reserved for sequence numbers.1 to 3 ---Page Number. 4 to 6 ---Line Number • Column 7 is an indicator column and has specialmeaning to the compiler.Hyphen ( - ) indicates continuation. Slash ( / ) indicates comment line, the comment line will be printed after page ejection. Asterisk ( * ) indicates comment line, no such page ejection. • Columns 8 to 11 are called Area A. All COBOL DIVISIONs, SECTIONs, paragraphs and some special entries must begin in Area A. • Columns 12 to 72 are called Area B. All COBOL statements must begin in Area B.

  12. COBOL coding sheet Almost all COBOL compilers treat a line of COBOL code as if it contained two distinct areas. These are - AREA A *) Between Column 8 to 11 *) Division, Section, Paragraph names, FD entries & 01 level entries must start in Area A AREA B *) Between Column 12 to 72 *) All Sentences & Statements start in Area B

  13. coding rules • Columns 73 to 80 are identification area. Anything written in this area , will be ignored by the compiler but will appear in the source listing. • Columns 1-6 and 73-80 optional and rarely used today • Column 7 for continuation, comment, starting new page • Columns 8-72 for COBOL program statements Column 7 * (asterisk) designates entire line as comment / (slash) forces page break when printing source listing - (dash) to indicate continuation of nonnumeric literal

  14. Margin Rules • Columns 8-72 divided into two areas • Area A - columns 8, 9, 10, 11 • Area B - columns 12-72 • Division, section and paragraph-names must all begin in Area A • First letter of name must begin in column 8, 9, 10 or 11 • Entry may extend into Area B • All other statements, clauses, and sentences begin anywhere in Area B (column 12, 13, 14, etc.) • Select entries in ENVIRONMENT DIVISION • Data description entries in DATA DIVISION • All PROCEDURE DIVISION instructions

  15. Data names and Identifiers • Data names Are named memory locations. • Data Names must be described in the DATA DIVISION before they can be used in the PROCEDURE DIVISION. • Can be of elementary or group type. • Can be subscripted for Arrays. • Are user defined words (refer Rules) . • Indexed or subscripted is normally referred to by the general term identifier. • Example---A12, sum-natural, net-pay,…

  16. Rules for forming User-defined words/Data names • Can be at most 30 characters in length. • At least one alphabetic character. • Only alphabets, digits and hyphen are allowed. • Blanks are not allowed. • May not begin or end with a hyphen. • Should not be a COBOL reserved word like ADD,SUBTRACT,MOVE,DISPLAY etc….

  17. Data-Name Guidelines • Use meaningful data-names that describe contents of field • Use prefixes or suffixes in data-names when appropriate • -IN and -OUT for fields (Emp-Salary-IN and Emp-Salary-OUT) • -FILE and -RECORD for file and record names (Emp-File and Emp-Record) • Amount-Due-In instead of A1

  18. Identify the valid data-names • Identify the valid data-names • Date-Of-Birth • Amount$Out • -First-Name • 98-6 • Time out • ADD

  19. Literals • Literals are symbols whose value does not change in a program. • A data name may have different values at different points of time whereas a literal means the specific value which remains unchanged throughout the execution of the program. For this reason a literal is often called a constant. Example--- MOVE 0 to sum. (Here 0 is literal) • There are 3 types of literals namely (1) Numeric literals. (2) Non-numeric literals. (3) Figurative constants.

  20. Rules for Numeric Literals • A numeric literal can be formed with the help of digits only. • The maximum number of digits allowed in a numeric literal varies from compiler to compiler. can have a maximum of 18 digits. • + or - sign may be included to left of first digit. • Decimal point permitted within literal. May not follow last digit.Valid numeric literals23 , +2359.4 , .125 , -68734

  21. Rules for Nonnumeric Literals • Composed of characters which are enclosed within quotation marks. • Generally used for output messages or headings. • Any character in COBOL character set except quotation mark. • The maximum number of characters that are allowed is compiler dependent. ANSI 74-120 characters.Valid Nonnumeric Literals “123 Main St.” “$14.99” “12,342” “Enter a value from 1 to 10”

  22. Figurative Constants • These are literals representing values that may be frequently used by most programs. • These are given some fixed names and when the compiler recognizes these names it sets up the corresponding values in the object program. • Example--- MOVE ZERO TO sum. • The following is the list of figurative constants and their meanings.

  23. Literals – Figurative Constants Figurative constants Meaning ZERO(S) or ZEROES Represents the value 0, one or more depending on the context SPACE(S) Represents one or more spaces HIGH-VALUE(S) Represents the highest value LOW-VALUE(S) Represents the lowest value QUOTE(S) Represents single or double quotes ALL literalFill With Literal

  24. 01 GrossPay PIC 9(5)V99 VALUE 13.5. MOVE TO GrossPay. ZERO ZEROS ZEROES StudentName M I K E ¨ ¨ ¨ ¨ ¨ ¨ Figurative Constants - Examples GrossPay 0 0 0 1 3 5 0 ñ l 01 StudentName PIC X(10) VALUE "MIKE". MOVE ALL "-" TO StudentName.

  25. 01 GrossPay PIC 9(5)V99 VALUE 13.5. MOVE TO GrossPay. ZERO ZEROS ZEROES StudentName - - - - - - - - - - Figurative Constants - Examples GrossPay 0 0 0 0 0 0 0 ñ l 01 StudentName PIC X(10) VALUE "MIKE". MOVE ALL "-" TO StudentName.

  26. Continuation of Lines • A statement or an entry may be continued to the area B of the next line as and when necessary. • A hyphen(-) is used in the indicator field for continuation of lines. • Actually, a hyphen in the indicator field means that the first non-blank character in the area B of the current line is the character immediately following the last non-blank character of the previous line. • Example—In case of non numeric literal Indicator line Area A Area B Continued line “Enter the Continuation Line - “Number”.

  27. Is Cobol still used ? • 75% of all business data is processed in COBOL. • There are between 180 billion and 200 billion lines of COBOL code in use worldwide. • 15% of all new applications (5 billion lines) through 2009 will be in COBOL.

  28. Thank You

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