Influencing runtime behavior#
These options affect the runtime behavior of programs compiled with GNU Fortran.
- -fconvert=conversion#
Specify the representation of data for unformatted files. Valid values for conversion on most systems are:
native
, the default;swap
, swap between big- and little-endian;big-endian
, use big-endian representation for unformatted files;little-endian
, use little-endian representation for unformatted files.On POWER systems which suppport
-mabi=ieeelongdouble
, there are additional options, which can be combined with others with commas. Those are-fconvert=r16_ieee
Use IEEE 128-bit format forREAL(KIND=16)
.-fconvert=r16_ibm
Use IBM long double format forREAL(KIND=16)
.
This option has an effect only when used in the main program. The
CONVERT
specifier and the GFORTRAN_CONVERT_UNIT environment variable override the default specified by-fconvert
.
- -frecord-marker=length#
Specify the length of record markers for unformatted files. Valid values for
length
are 4 and 8. Default is 4. This is different from previous versions of gfortran, which specified a default record marker length of 8 on most systems. If you want to read or write files compatible with earlier versions of gfortran, use-frecord-marker=8
.
- -fmax-subrecord-length=length#
Specify the maximum length for a subrecord. The maximum permitted value for length is 2147483639, which is also the default. Only really useful for use by the gfortran testsuite.
- -fsign-zero#
When enabled, floating point numbers of value zero with the sign bit set are written as negative number in formatted output and treated as negative in the
SIGN
intrinsic.-fno-sign-zero
does not print the negative sign of zero values (or values rounded to zero for I/O) and regards zero as positive number in theSIGN
intrinsic for compatibility with Fortran 77. The default is-fsign-zero
.