Methods of Specifying the Data Format: Overview
There are six methods of specifying a nonnative numeric format for unformatted
data:
- Setting an environment variable for a specific unit
number before the file is opened. The environment variable is named FORT_CONVERTn,
where n is the unit number. See Environment
Variable FORT_CONVERTn Method.
- Setting an environment variable for a specific file
name extension before the file is opened. The environment variable is
named FORT_CONVERT.ext or FORT_CONVERT_ext, where ext
is the file name extension (suffix). See Environment
Variable FORT_CONVERT.ext or FORT_CONVERT_ext Method.
- Setting an environment variable for a set of units
before any files are opened. The environment variable is named F_UFMTENDIAN.
See Environment Variable F_UFMTENDIAN Method.
- Specifying the CONVERT keyword in the OPEN statement
for a specific unit number. See OPEN Statement
CONVERT Method.
- Compiling the program with an OPTIONS statement that
specifies the CONVERT=keyword qualifier. This method affects all
unit numbers using unformatted data specified by the program. See OPTIONS
Statement Method.
- Compiling the program with the command-line -convert keyword
option, which affects all unit numbers that use unformatted data specified
by the program. See Compiler Option -convert Method.
If none of these methods are specified, the native LITTLE_ENDIAN format
is assumed (no conversion occurs between disk and memory).
Any keyword listed in Supported Native and Nonnative
Numeric Formats can be used with any of these methods,
except for the Environment Variable F_UFMTENDIAN
Method, which supports only LITTLE_ENDIAN and BIG_ENDIAN.
If you specify more than one method, the order of precedence when you
open a file with unformatted data is to:
- Check for an environment variable (FORT_CONVERTn)
for the specified unit number (applies to any file opened on a particular
unit).
- Check for an environment variable (FORT_CONVERT.ext
is checked before FORT_CONVERT_ext) for the specified file name
extension (applies to all files opened with the specified file name extension).
- Check for an environment variable (F_UFMTENDIAN)
for the specified unit number (or for all units).
- Check the OPEN statement CONVERT qualifier.
- Check whether an OPTIONS statement with a CONVERT=keyword
qualifier was present when the program was compiled.
- Check whether the compiler option -convert
keyword was present when the program was compiled.