From COBOL to OOP
Written for the experienced COBOL programmer, this nuts and bolts guide offers a comprehensive introduction to OOP techniques, and provides a migration of 10 million lines of COBOL code to object-oriented programming.
TABLE OF CONTENTS From COBOL to OOP
3.4: Arrays, Strings, Records
3.4 Arrays, Strings, Records
Simple data types are not sufficient
So far, we have introduced simple data types that can be used, for example, to manage individual characters or numbers. These data types are important, but they are not sufficient. Think only of the simplest applications, for example from the accounting discipline an account has not only a balance (which could easily be mapped with a floating-point number) but also a name, a unique number, and so on; and it also requires a list (table) of postings.
We can see that the simple data types are not sufficient, which means we need composite types. Simple forms of these composite types are arrays, strings, or records. These forms are also known in COBOL: Arrays correspond to the OCCURS entries of COBOL, strings are character strings, and records are used like COBOL group fields.
3.4.1 Arrays
Homogeneous data structure: all elements have the same type
An array is a table of elements (variable cells). All elements are of the same type, so we also speak of a homogeneous data structure. The variable, which was declared as an array, always identifies the entire array. When accessing this variable, we always access the array. If we want to access a single element of that array, access is possible by using the index. Arrays are known from COBOL; for example, an array with 100 integer elements could be defined as follows in COBOL: A OCCURS 100 TIMES PIC X(4).
Array Definition
Delphi: array...
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