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 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.  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.

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.  PROGRAM-ID is used to name the program. This is the only paragraph that is required in the ID DIVISION.  AUTHOR used to code the programmer's name  INSTALLATION used 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 machine- dependent.  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.  Sentence : A statement or series of statement ending with a period (.)  STOP RUN : Specifies end of the program.

COBOL Layout/COBOL Code Sheet (1 - 80) Sequence Number This area was originally designed for entering line numbers on each individual line of code 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 Area A This area is used to enter division headers, section headers, paragraph names, file indicators and level 01 items Area B This area is used to enter any statement that doesn't go in Area A 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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