You can use this method to specify a non-native numeric format for each specified file name extension (suffix). You specify the numeric format at run time by setting the appropriate environment variable before an implicit or explicit OPEN to one or more unformatted files. You can use the format FORT_CONVERT.ext or FORT_CONVERT_ext (where ext is the file extension or suffix). The FORT_CONVERT.ext environment variable is checked before FORT_CONVERT_ext environment variable (if ext is the same).
For example, assume you have a previously compiled program that reads numeric data from one file and writes to another file using unformatted I/O statements. You want the program to read nonnative big endian (IEEE floating-point) format from a file with a .dat file extension extension and write that data in native little endian format to a file with a extension of .data. In this case, the data is converted from big endian IEEE format to native little endian IEEE memory format (S_float and T_float) when read from file.dat, and then written without conversion in native little endian IEEE format to the file with a suffix of .data, assuming that environment variables FORT_CONVERT.DATA and FORT_CONVERTn (for that unit number) are not defined.
Without requiring source code modification or recompilation of this program, the following command sequence sets the appropriate environment variables before running the program (c:\proj2\cvbigend.exe):
set FORT_CONVERT.DAT=BIG_ENDIAN
c:\proj2\cvbigend.exe
The FORT_CONVERTn method takes precedence over this method. When the appropriate environment variable is set when you open the file, the FORT_CONVERT.ext or FORT_CONVERT_ext environment variable is used if a FORT_CONVERTn environment variable is not set for the unit number.
The FORT_CONVERTn and the FORT_CONVERT.ext or FORT_CONVERT_ext environment variable methods take precedence over the other methods. For instance, you might use this method to specify that a unit number will use a particular format instead of the format specified in the program (perhaps for a one-time file conversion).
You can set the appropriate environment variable using the format FORT_CONVERT.ext or FORT_CONVERT_ext. If you also use Compaq Fortran on U*X systems, consider using the FORT_CONVERT_ext form, because a dot (.) cannot be used for environment variable names on certain U*X command shells. If you do define both FORT_CONVERT.ext and FORT_CONVERT_ext for the same extension (ext), the file defined by FORT_CONVERT.ext is used.
On Windows systems, the file name extension (suffix) is not case-sensitive. The extension must be part of the file name (not the directory path).