The CONVERT specifier indicates a nonnative numeric format for unformatted data. It takes the following form:
| 'LITTLE_ENDIAN' 1 | Little endian integer data 2 and IEEE® floating-point data. 3 |
| 'BIG_ENDIAN' 1 | Big endian integer data 2 and IEEE floating-point data. 3 |
| 'CRAY' | Big endian integer data 2 and CRAY® floating-point data of size REAL(8) or COMPLEX(8). |
| 'FDX' | Little endian integer data 2 and Compaq (formerly DIGITAL) VAXTM floating-point data of format F_floating for REAL(4) or COMPLEX(4), D_floating for size REAL(8) or COMPLEX(8), and IEEE X_floating for REAL(16) or COMPLEX(16). 4 |
| 'FGX' | Little endian integer data 2 and Compaq VAX floating-point data of format F_floating for REAL(4) or COMPLEX(4), G_floating for size REAL(8) or COMPLEX(8), and IEEE X_floating for REAL(16) or COMPLEX(16). 4 |
| 'IBM' | Big endian integer data 2 and IBM® System\370 floating-point data of size REAL(4) or COMPLEX(4) (IBM short 4), and size REAL(8) or COMPLEX(8) (IBM long 8). |
| 'VAXD' | Little endian integer data 2 and Compaq VAX floating-point data of format F_floating for size REAL(4) or COMPLEX(4), D_floating for size REAL(8) or COMPLEX(8), and H_floating for REAL(16) or COMPLEX(16). 4 |
| 'VAXG' | Little endian integer data 2 and Compaq VAX floating-point data of format F_floating for size REAL(4) or COMPLEX(4), G_floating for size REAL(8) or COMPLEX(8), and H_floating for REAL(16) or COMPLEX(16). 4 |
| 'NATIVE' | No data conversion. This is the default. |
| 1 INTEGER(1) data is the same for little endian and big endian. 2 Of the appropriate size: INTEGER(1), INTEGER(2), INTEGER(4), or INTEGER(8) 3 Of the appropriate size and type: REAL(4), REAL(8), REAL(16), COMPLEX(4), COMPLEX(8), or COMPLEX(16) 4 U*X only | |
You can use CONVERT to specify multiple formats in a single program, usually one format for each specified unit number.
When reading a nonnative format, the nonnative format on disk is converted to native format in memory. If a converted nonnative value is outside the range of the native data type, a run-time message appears.
There are other ways to specify numeric format for unformatted files: you can specify an environment variable, the compiler option /convert, or OPTIONS/CONVERT. The following shows the order of precedence:
| Method Used | Precedence |
|---|---|
| An environment variable | Highest |
| OPEN(CONVERT=convert) | . |
| OPTIONS/CONVERT | . |
| The /convert:keyword compiler option | Lowest |
The /convert compiler option and OPTIONS/CONVERT affect all unit numbers used by the program, while environment variables and OPEN (CONVERT=) affect specific unit numbers.
The following example shows how to code the OPEN statement to read unformatted CRAY® numeric data from unit 15, which might be processed and possibly written in native little endian format to unit 20:
OPEN (CONVERT='CRAY', FILE='graph3.dat', FORM='UNFORMATTED',
1 UNIT=15)
...
OPEN (FILE='graph3_native.dat', FORM='UNFORMATTED', UNIT=20)
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