www.delorie.com/gnu/docs/gcc/g77_53.html   search  
Buy the book!

Using and Porting GNU Fortran

[ < ] [ > ]   [ << ] [ Up ] [ >> ]         [Top] [Contents] [Index] [ ? ]

8.7.2 Constants

(Corresponds to Section 4.2 of ANSI X3.9-1978 FORTRAN 77.)

A typeless constant has one of the following forms:


binary-digits, octal-digits, and hexadecimal-digits are nonempty strings of characters in the set `01', `01234567', and `0123456789ABCDEFabcdef', respectively. (The value for `A' (and `a') is 10, for `B' and `b' is 11, and so on.)

A prefix-radix constant, such as `Z'ABCD'', can optionally be treated as typeless. See section Options Controlling Fortran Dialect, for information on the `-ftypeless-boz' option.

Typeless constants have values that depend on the context in which they are used.

All other constants, called typed constants, are interpreted--converted to internal form--according to their inherent type. Thus, context is never a determining factor for the type, and hence the interpretation, of a typed constant. (All constants in the ANSI FORTRAN 77 language are typed constants.)

For example, `1' is always type INTEGER(KIND=1) in GNU Fortran (called default INTEGER in Fortran 90), `9.435784839284958' is always type REAL(KIND=1) (even if the additional precision specified is lost, and even when used in a REAL(KIND=2) context), `1E0' is always type REAL(KIND=2), and `1D0' is always type REAL(KIND=2).

  webmaster     delorie software   privacy  
  Copyright 2003   by The Free Software Foundation     Updated Jun 2003