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CHAPTER 2 Cobol Language Fundamentals

CHAPTER 2 Cobol Language Fundamentals. BASIC STRUCTURE OF A COBOL PROGRAM. CODING RULES. A COBOL statement is subdivided into 72 positions or columns. Column 7 of a COBOL program has three primary purposes:

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CHAPTER 2 Cobol Language Fundamentals

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  1. CHAPTER 2Cobol Language Fundamentals Structured COBOL Programming, Stern & Stern, 9th Edition

  2. BASIC STRUCTURE OF A COBOL PROGRAM

  3. CODING RULES • A COBOL statement is subdivided into 72 positions or columns. • Column 7 of a COBOL program has three primary purposes: 1. By coding an * (asterisk) in column 7, an entire line can be designated as a comment. 2. It can be used to force the printing of subsequent instructions on the next page of the source listing. 3. It can be used for the continuation of nonnumeric literals. Structured COBOL Programming, Stern & Stern, 9th Edition

  4. DEBUGGING TIP • Use uppercase letters for instructions; • use lowercase letters for comments. • Page-Eject with a Slash (/) in Column 7 can also be used to skip to the next page when the source listing is being printed. Structured COBOL Programming, Stern & Stern, 9th Edition

  5. CODING RULES: Areas A and B • Positions 8--72 of a standard COBOL program contain program statements: • Column 8 is labeled the A area • Column 12 is labeled the B area • Entries in Area A, may begin in position 8, 9, 10, or 11. • Most often, Area A entries begin in position 8. • If an entry is to be coded in Area B, it may begin anywhere after position 11. Structured COBOL Programming, Stern & Stern, 9th Edition

  6. TYPES OF COBOL ENTRIES Divisions, sections, and paragraphs begin in Area A. Examples include: • DIVISIONS IDENTIFICATION DIVISION. ENVIRONMENT DIVISION. DATA DIVISION. PROCEDURE DIVISION. • SECTIONS FILE SECTION. WORKING-STORAGE SECTION. Structured COBOL Programming, Stern & Stern, 9th Edition

  7. TYPES OF COBOL ENTRIES Divisions, sections, and paragraphs begin in Area A. Examples include: • PARAGRAPHS PROGRAM-ID. 0-MAIN-MODULE. 1-BUILD-DETAIL-LINE. • Statements and sentences begin in Area B; for example: SELECTPAYROLLASSIGN TO DISK. ADDAMT-INTO TOTAL. Structured COBOL Programming, Stern & Stern, 9th Edition

  8. TYPES OF COBOL ENTRIES • MARGIN RULES 1. Division, section, and paragraph-names begin in Area A. 2. All other statements, clauses, and sentences begin in Area B. Structured COBOL Programming, Stern & Stern, 9th Edition

  9. CODING REQUIREMENTS OF THE IDENTIFICATION DIVISION Structured COBOL Programming, Stern & Stern, 9th Edition

  10. Paragraphs in the IDENTIFICATION DIVISION IDENTIFICATION DIVISION. PROGRAM-ID. program-name. [AUTHOR. [comment-entry] . . .] [INSTALLATION. [comment-entry] . . .] [DATE-WRITTEN. [comment-entry] . . .] [DATE-COMPILED. [comment-entry] . . .] [SECURITY. [comment-entry] . . .] Structured COBOL Programming, Stern & Stern, 9th Edition

  11. Rules for Interpreting Instruction Formats 1. Uppercase words are COBOL reserved words 2. Underlined words are required. 3. Lowercase words represent user-defined entries. 4. Braces { } denote that one of the enclosed items is required. Structured COBOL Programming, Stern & Stern, 9th Edition

  12. Rules for Interpreting Instruction Formats 5. Brackets [ ] mean the clause or paragraph is optional. 6. If punctuation is specified in the format, it is required. 7. Dots … or ellipses (…) means additional entries of the same type may be optionally added. Structured COBOL Programming, Stern & Stern, 9th Edition

  13. COBOL 2000+ CHANGES • All paragraphs AUTHOR through SECURITY have been deleted from the COBOL 2000+ standard since they can be easily replaced with comments. Structured COBOL Programming, Stern & Stern, 9th Edition

  14. QUESTIONS?

  15. SELF-TEST 1. If an entry must begin in Area A, it may begin in position _____ ; if an entry must begin in Area B, it may begin in position _____ . Solution: 8, 9, 10, or 11; 12, 13, 14, and so on Structured COBOL Programming, Stern & Stern, 9th Edition

  16. SELF-TEST 2. The four divisions of a COBOL program must appear in order as _____ ; _____ ; _____ ; and, _____ . Solution: IDENTIFICATION; ENVIRONMENT; DATA; PROCEDURE Structured COBOL Programming, Stern & Stern, 9th Edition

  17. SELF-TEST 3. What entries must be coded beginning in Area A? Solution: Division, section, and paragraph-names Structured COBOL Programming, Stern & Stern, 9th Edition

  18. SELF-TEST 4. Most entries such as PROCEDURE DIVISION instructions are coded in Area _____ . Solution: B Structured COBOL Programming, Stern & Stern, 9th Edition

  19. SELF-TEST 5. _____ and _____ must each appear on a separate line. All other entries may have several statements on the same line. Solution: Division names; section names Structured COBOL Programming, Stern & Stern, 9th Edition

  20. SELF-TEST 6. The first two entries of a COBOL program must always be _____ and _____ . Solution: IDENTIFICATION DIVISION. PROGRAM-ID. program-name. Structured COBOL Programming, Stern & Stern, 9th Edition

  21. SELF-TEST 7. Each of the preceding entries must be followed by a _____ , which, in turn, must be followed by a ____ . Solution: period; space or blank Structured COBOL Programming, Stern & Stern, 9th Edition

  22. SELF-TEST 9. Code the IDENTIFICATION DIVISION for a program called EXPENSES for a corporation, Dynamic Data Devices, Inc., written January 18, 2007. This program has a security classification and is available to authorized personnel only. It produces a weekly listing by department of all operating expenses. Structured COBOL Programming, Stern & Stern, 9th Edition

  23. SELF-TEST 9. Suggested solution: IDENTIFICATION DIVISION. PROGRAM-ID. EXPENSES. *AUTHOR. N. B. STERN. *INSTALLATION. DYNAMIC DATA DEVICES, INC. *DATE-WRITTEN. 1/18/2007. *DATE-COMPILED. 1/18/2007. *SECURITY. AUTHORIZED PERSONNEL ONLY. Structured COBOL Programming, Stern & Stern, 9th Edition

  24. THE SECTIONS OF THE ENVIRONMENT DIVISION • The ENVIRONMENT DIVISION is the only machine-dependent division of a COBOL program. • Entries in this division will depend upon: • (1) the computer system and • (2) the specific devices or hardware used in the program.* *Interactive programs that use keyed data as input and display screen output will not need this division. Structured COBOL Programming, Stern & Stern, 9th Edition

  25. THE CONFIGURATION SECTION • Supplies information about the computer on which the COBOL program will be compiled and executed. SOURCE-COMPUTER: • The computer that will be used for compiling the program. OBJECT-COMPUTER: - The computer that will be used for executing or running the program. • SOURCE- COMPUTER and OBJECT-COMPUTER are coded primarily as documentation entries. Structured COBOL Programming, Stern & Stern, 9th Edition

  26. The CONFIGURATION SECTION • All section names, like division names, are coded in Area A. • The CONFIGURATION SECTION, if coded, will follow the ENVIRONMENT DIVISION entry in Area A. • SOURCE-COMPUTER and OBJECT-COMPUTER, as paragraph-names, would also be coded in Area A. Structured COBOL Programming, Stern & Stern, 9th Edition

  27. CONFIGURATION SECTION EXAMPLE ENVIRONMENT DIVISION. CONFIGURATION SECTION. SOURCE-COMPUTER.IBM iSeries. OBJECT-COMPUTER.IBM iSeries. Structured COBOL Programming, Stern & Stern, 9th Edition

  28. INPUT-OUTPUT SECTION • The INPUT-OUTPUT SECTION optionally follows the CONFIGURATION SECTION • It supplies information concerning the input and output devices used in the program by means of a FILE-CONTROL paragraph. • In the FILE-CONTROL paragraph, a file-name is designated and assigned to a device for each file used in the program. Structured COBOL Programming, Stern & Stern, 9th Edition

  29. INPUT-OUTPUT SECTION • The FILE-CONTROL paragraph consists of SELECT statements • each is coded in Area B followed by a period. • A SELECT statement • defines a file-name. • assigns a device name to that file*. A file is the major collection of data for a given application. Structured COBOL Programming, Stern & Stern, 9th Edition

  30. INPUT-OUTPUT SECTION • Batch processing applications have an input file and an output file. • Interactive processing allows input using a keyboard; • therefore, it is not necessary to establish an input file. Structured COBOL Programming, Stern & Stern, 9th Edition

  31. INPUT-OUTPUT SECTION • If the output is printed or saved on disk, an output file must exist in the ENVIRONMENT DIVISION. • If the output is displayed on a screen, then no file declaration is necessary in the ENVIRONMENT DIVISION. - When this is the case, the ENVIRONMENT DIVISION may be entirely omitted. Structured COBOL Programming, Stern & Stern, 9th Edition

  32. ASSIGNING FILES TO DEVICES IN THE ENVIRONMENT DIVISION

  33. OVERALL FORMAT • The instruction format for the SELECT statement follows: SELECTfile-name-1 ASSIGN TO implementor-name-1 [ORGANIZATION IS LINESEQUENTIAL] • The implementor-name is a machine-dependent device specification that is typically provided by the computer center. Structured COBOL Programming, Stern & Stern, 9th Edition

  34. OVERALL FORMAT REVIEW OF INSTRUCTION FORMAT RULES 1. Uppercase words are reserved words; lowercase words are user-defined. 2. Underlined words are required in the statement. 3. Two lines are used for a SELECT statement • the second line is indented for “ readability” Structured COBOL Programming, Stern & Stern, 9th Edition

  35. OVERALL FORMAT File-Name Rules 1. The file-name assigned to each device must conform to the rules for forming user-defined words. 2. A user-defined word is a word chosen by the programmer to represent some element in a program such as a file-name: Structured COBOL Programming, Stern & Stern, 9th Edition

  36. OVERALL FORMAT • Rules for Forming User-Defined Words (Such as File-Names) 1. 1 to 30 characters. 2. Letters, digits, and hyphens (-) only. 3. No embedded blanks • It is best to use hyphens to separate words (e.g., EMPLOYEE-NAME) 4. At least one alphabetic character. Structured COBOL Programming, Stern & Stern, 9th Edition

  37. OVERALL FORMAT 5. May not begin or end with a hyphen. 6. No COBOL reserved words such as DATA, DIVISION, etc. • A full list of reserved words appears in Appendix A and in the COBOL Syntax Reference Guide. Structured COBOL Programming, Stern & Stern, 9th Edition

  38. THE NET If you do not have a COBOL SyntaxReference Guide, it can be downloaded from: http://www.wiley.com/cobol/ Structured COBOL Programming, Stern & Stern, 9th Edition

  39. OVERALL FORMAT • A SELECT statement must be specified for each file in the program,. • If a program requires a disk file as input and produces a printed report as an output file, two SELECT statements will be specified. • one file-name will be assigned to the disk file • the other to the print file. Structured COBOL Programming, Stern & Stern, 9th Edition

  40. DEBUGGING TIP • File names assigned by the programmer should be meaningful. Examples: SALES-IN SALES-REPORT-OUT Structured COBOL Programming, Stern & Stern, 9th Edition

  41. OVERALL FORMAT Implementor-Names or Device Specifications • Most systems enable the programmer to access frequently used devices by special device names. Structured COBOL Programming, Stern & Stern, 9th Edition

  42. OVERALL FORMATImplementor-Names or Device Specifications The following are common shorthand device specifications that you will use on our iSeries system: Printer PRINTER followed by a printer file object name Disk DISK followed by a file or database object name Structured COBOL Programming, Stern & Stern, 9th Edition

  43. SELECT Statements for PCs 1. Device Specification on PCs (a) The drive on which the disk file appears followed by a colon (e.g., C:, D:, etc.). • If your file is in a subdirectory, you must specify that as well (e.g., C:\COBOL). Structured COBOL Programming, Stern & Stern, 9th Edition

  44. SELECT Statements for PCs (b) The file-name for that disk file, where the rules for forming file- names are dependent on the operating system. • The device name for these PC versions of COBOL is usually enclosed in quotes: SELECT EMPLOYEE-FILE ASSIGN TO 'C:EMPFILE'. SELECT INVENTORY-FILE ASSIGN TO 'C:\INVENTORY\INVFILE.DAT'. Structured COBOL Programming, Stern & Stern, 9th Edition

  45. SELECT Statements for iSeries 1. Device Specification on the iSeries (a) Refer to the file object name. i.e., assume there is physical file named ROSTER that you want the program to access … You will code SELECT ROSTER-FILE-INASSIGN TO DISK-ROSTER. Structured COBOL Programming, Stern & Stern, 9th Edition

  46. CHAPTER SLIDES END HERE CHAPTER SUMMARY COMES NEXT Structured COBOL Programming, Stern & Stern, 9th Edition

  47. CHAPTER SUMMARY I. The IDENTIFICATION DIVISION A. The IDENTIFICATION DIVISION and its paragraphs are used for documentation and do not affect the execution of the program. B. The first two items to be coded in a program are: IDENTIFICATION DIVISION. PROGRAM-ID. program-name. C. A program name that is up to eight characters, letters and digits only, is acceptable on all computers. Structured COBOL Programming, Stern & Stern, 9th Edition

  48. CHAPTER SUMMARY E. Comments can be included in the IDENTIFICATION DIVISION, as well as all other divisions, by coding an * in position 7. • This makes the entire line a comment. • We encourage you to use comments throughout your programs for documentation. F. A slash (/) in column 7 will cause the subsequent lines to be printed on the next page of the source listing. Structured COBOL Programming, Stern & Stern, 9th Edition

  49. CHAPTER SUMMARY II. The ENVIRONMENT DIVISION A. The format for the ENVIRONMENT DIVISION is: ENVIRONMENT DIVISION. CONFIGURATION SECTION. SOURCE-COMPUTER. computer-name OBJECT-COMPUTER. computer-name INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT file-name-1 ASSIGN TO implementor-name-1 Structured COBOL Programming, Stern & Stern, 9th Edition

  50. CHAPTER SUMMARY II. The ENVIRONMENT DIVISION • Fully interactive programs that use keyed data as input and screen displays as output are not required to have an ENVIRONMENT DIVISION. Structured COBOL Programming, Stern & Stern, 9th Edition

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