Short INTEGERS in standard Fortran 77

ABSTRACT

Standard Fortran 77 has an INTEGER data type, but only one size of integers. On a 32-bit word-size machine an INTEGER will normally occupy 32 bits, or four 8-bit bytes, and can contain an integer magnitude in excess of 2 billion. Often an application deals with integer values of far less magnitude than this, and in such cases, especially where memory is not abundant, it is advantageous to use smaller storage units for integer values. The most common situation is when the integer values are not greater than 32767 in magnitude, in which case two bytes (16 bits) of storage are sufficient. Many Fortran compilers allow short integer declarations, in the form of INTEGER*2, to provide for two-byte integer storage. In some cases even one byte is sufficient (for example when the integer magnitude is not greater than 127), and INTEGER*1 is provided by an occasional compiler.