Input and Output

Abstract

There appear to be three dominant strategies for handling the input and output of data in programming languages:

• 1. Format specifications: Format specifications are based upon the idea that an input or output statement has an associated format description, which specifies the layout of data values and the use of spacing. This view is used in Fortran and PL/I.

• 2. Picture specifications: With picture specifications, a declared data item has an associated picture clause describing the form that such an item would have on an input or output device. This view appears in Cobol and PL/I.

• 3. Specialized subprograms: Here the layout of data for different kinds of data items is specified in specialized subprograms. For example, we may have one subprogram to output integers, and another subprogram to output character strings. This view appears in Simula 67, Pascal, and Algol 68.