IBMMainframes COBOL Class1 Background and History COBOL is

IBM-Mainframes COBOL Class-1

Background and History § COBOL is an acronym for: Common Business Oriented Language § COBOL was developed in 1959 by the Conference on Data Systems Languages (CODASYL). § § COBOL was designed to solve business problems § COBOL was designed to be portable, so that programs could be adapted from one computer system to run on another, simply by making a few changes in one isolated section of the code. COBOL was designed to be English-like, so that the reader, even a non-programmer, could get an idea of what was going on in the program, simply by reading the code.

Background and History Contd. . § Since 1960, the American National Standards Institute (ANSI) was responsible for developing new COBOL standards. § Three ANSI standards for COBOL have been produced: § in 1968, 1974 and 1985 (currently Using ). § Object-oriented COBOL is the fourth edition in the continuing evolution of ANSI/ISO standard COBOL.

Structure of COBOL Program § The organization of a COBOL program is hierarchical. It's not necessarily required for all of components to be present for the hierarchical relationship to exist . . Program. . Division. . Section. . Paragraph. . Sentence. . Statement. . Clause / Phrase / VERBS. . Word (. . Character)

COBOL Program Organization (Division) § We have four divisions in every COBOL program IDENTIFICATION, ENVIRONMENT, DATA, and PROCEDURE. § IDENTIFICATION DIVISION The first division of COBOL program; used for documentation purposes. § used to name the program. This is the only paragraph that is required in the ID DIVISION. § AUTHOR used § INSTALLATION used § PROGRAM-ID is to code the programmer's name to code the programmer's employer's name DATE-WRITTEN & DATE-COMPILED used to code the date the program was written & compiled § SECURITY used to code the security level of the program

Division’s § Contd. . ENVIRONMENT DIVISION Provides information on the equipment and file used with the program and only division that may be machinedependent. § § Two sections: CONFIGURATION and INPUT-OUTPUT Section CONFIGURATION SECTION optional section is used to specify the type of computer equipment SOURCE-COMPUTER used to compile the program. OBJECT-COMPUTER used to execute the program. §INPUT-OUTPUT SECTION used to specify input/output files used in the program. FILE-CONTROL used to associate the files to be used in the program with specific I/O devices.

Division’s Contd. . § DATA DIVISION : Defines and describes all the data to be used in a program/To declare variables. § Sections: FILE, WORKING-STORAGE, LINKAGE, REPORT, and COMMUNICATION SECTIONS § FILE SECTION is used to define the files record layout that will be used in the program. § WORKING-STORAGE is used to define any data that will be used in the program that is not part of a file section. § LINKAGE SECTION is used in a subprogram to define data that will be passed as arguments to the routine. § REPORT SECTION can be used to produce standard control break driven reports. COMMUNICATION SECTION is used for communicating between two programs running simultaneously on a computer

Division’s Contd. . § PROCEDURE DIVISION This contains the instruction to be executed in the program § This division consists of a series of procedures called paragraphs, each designed to perform a specific function. § Paragraph Consists of a paragraph name and a series of procedural statements designed to perform a desired function. § § Statement : An instruction. § STOP RUN : Specifies end of the program. Sentence : A statement or series of statement ending with a period (. )

COBOL Layout/COBOL Code Sheet (1 - 80) 1. 1 -6 Sequence Number This area was originally designed for entering line numbers on each individual line of code. 2. 7 Comments /Continuation This area is used to designate a line as either a comment or a continuation for previous line code. • * This line is a comment. • This line is a continuation of the previous line. 3. 8 -11 Area A This area is used to enter division headers, section headers, paragraph names, file indicators and level 01 items. 4. 12 -72 Area B This area is used to enter any statement that doesn't go in Area A. 5. 73 -80 Program Identification This area has been used by programmers as a way to mark individual lines of code,

My First COBOL Program § Hello world! Program IDENTIFICATION DIVISION. ( ID DIVISION ) PROGRAM-ID. HELLOPGM. - Max 8 character ENVIRONMENT DIVISION. DATA DIVISION. PROCRDURE DIVISION. DISPLAY ‘HELLO WORLD!’. STOP RUN. This Program gives HELLO WORLD! As Output.

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