Beginning COBOL for Programmers
Michael Coughlan
Language: English
Pages: 588
ISBN: 1430262532
Format: PDF / Kindle (mobi) / ePub
Beginning COBOL for Programmers is a comprehensive, sophisticated tutorial and modular skills reference on the COBOL programming language for established programmers. This book is for you if you are a developer who would like to—or must—add COBOL to your repertoire. Perhaps you recognize the opportunities presented by the current COBOL skills crisis, or are working in a mission critical enterprise which retains legacy COBOL applications. Whatever your situation, Beginning COBOL for Programmers meets your needs as an established programmer moving to COBOL.
Beginning COBOL for Programmers includes comprehensive coverage of ANS 85 COBOL features and techniques, including control structures, condition names, sequential and direct access files, data redefinition, string handling, decimal arithmetic, subprograms, and the report writer. The final chapter includes a substantial introduction to object-oriented COBOL.
Benefiting from over one hundred example programs, you’ll receive an extensive introduction to the core and advanced features of the COBOL language and will learn to apply these through comprehensive and varied exercises. If you've inherited some legacy COBOL, you’ll be able to grasp the COBOL idioms, understand the constructs, and recognize what's happening in the code you’re working with.
Today’s enterprise application developers will find that COBOL skills open new—or old—doors, and this extensive COBOL reference is the book to help you acquire and develop your COBOL skills.
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might want to group the YearOfBirth, MonthOfBirth, DayOfBirth data items as the group DateOfBirth. In addition, you might want to collect both these group items and some elementary items in an employee record description. In COBOL, you can easily create groups like these using group items. A group item in COBOL is a data item that is a collection of elementary and/or group data items. It is a heterogeneous data structure. In languages like Pascal and Modula-2, group items are referred to as
items. The chapter examined the assignment operation and discussed the data-manipulation opportunities afforded by the hierarchical structure of group item data declarations. But this is just an introduction to data declaration in COBOL. In the rest of this book, you expand your knowledge of data declaration by exploring such topics as the implicit redefinition of data items in the FILE SECTION, the operation of the REDEFINES clause, the preparation of data for output using edited pictures, the
CHAPTER 4 N PROCEDURE DIVISION BASICS Arithmetic Template Notes All the arithmetic verbs move the result of a calculation into a receiving data item according to the rules for a numeric move: that is, with alignment along the assumed decimal point and with zero-filling or truncation as necessary. In all the arithmetic verbs except COMPUTE, the result of the calculation is assigned to the rightmost data item(s). All arithmetic verbs must use numeric literals or numeric data items (PIC 9) that
condition is true. The StatementBlock following the ELSE (if used) executes, if the condition is false. The StatementBlock(s) can include any valid COBOL statement including further IF constructs. This allows for nested IF statements. One difference from many other programming languages is that when a condition is evaluated, it evaluates to either true or false. It does not evaluate to 1 or 0. The explicit scope delimiter END-IF was introduced in ANS 85 COBOL. In the previous versions of COBOL,
the employee file might be as shown in Example 7-3. Example 7-3. The DATA DIVISION Declarations for the Employee File. DATA DIVISION. FILE SECTION. FD EmployeeFile. 01 EmployeeDetails. 02 EmpSSN 02 EmpName. 03 EmpSurname 03 EmpForename 02 EmpDateOfBirth. 03 EmpYOB 03 EmpMOB 03 EmpDOB 02 EmpGender PIC 9(9). PIC X(15). PIC X(10). PIC PIC PIC PIC 9(4). 99. 99. X. In this example, the name EmployeeFile has been assigned as the internal name for the file. This name is then used in the program for