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Diffstat (limited to 'gcc/fortran/gfortran.texi')
| -rw-r--r-- | gcc/fortran/gfortran.texi | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/gcc/fortran/gfortran.texi b/gcc/fortran/gfortran.texi index 2644e40257e..50b64990985 100644 --- a/gcc/fortran/gfortran.texi +++ b/gcc/fortran/gfortran.texi @@ -618,7 +618,14 @@ Variable for swapping Endianness during unformatted write. @command{gfortran} implements a number of extensions over standard Fortran. This chapter contains information on their syntax and -meaning. +meaning. There are currently two categories of @command{gfortran} +extensions, those that provide functionality beyond that provided +by any standard, and those that are supported by @command{gfortran} +purely for backward compatibility with legacy compilers. By default, +@option{-std=gnu} allows the compiler to accept both types of +extensions, but to warn about the use of the latter. Specifying +either @option{-std=f95} or @option{-std=f2003} disables both types +of extensions, and @option{-std=legacy} allows both without warning. @menu * Old-style kind specifications:: @@ -630,6 +637,7 @@ meaning. * Hexadecimal constants:: * Real array indices:: * Unary operators:: +* Implicitly interconvert LOGICAL and INTEGER:: @end menu @node Old-style kind specifications @@ -786,6 +794,22 @@ operators without the need for parenthesis. X = Y * -Z @end smallexample +@node Implicitly interconvert LOGICAL and INTEGER +@section Implicitly interconvert LOGICAL and INTEGER +@cindex Implicitly interconvert LOGICAL and INTEGER + +As a GNU extension for backwards compatability with other compilers, +@command{gfortran} allows the implicit conversion of LOGICALs to INTEGERs +and vice versa. When converting from a LOGICAL to an INTEGER, the numeric +value of @code{.FALSE.} is zero, and that of @code{.TRUE.} is one. When +converting from INTEGER to LOGICAL, the value zero is interpreted as +@code{.FALSE.} and any non-zero value is interpreted as @code{.TRUE.}. + +@smallexample + INTEGER*4 i + i = .FALSE. +@end smallexample + @include intrinsic.texi @c --------------------------------------------------------------------- @c Contributing |