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NM callable only. Creates duplicate file descriptors for files opened for MULTI, SHARED, or EXCLUSIVE access. Syntax | |
I16 I32 I32V *
filenum:=HPFDUPLICATE(source,status,target);
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Functional Return | |
- filenum
16-bit signed integer (assigned functional return) Returns the actual file number used to duplicate the source file. This file number can be different than the file number requested in the target parameter. If an error occurs during the duplication process, a -1 value is returned.
Parameters | |
- source
32-bit signed integer by value (required) Specifies the file number to be duplicated. The file number must be a valid, open file.
- status
32-bit signed integer by reference (optional) Returns the status of the HPFDUPLICATE call. If an error occurs and this parameter was not specified, the functional return can be used to determine the success or failure of the call.
- target
32-bit signed integer by reference (optional) Specifies the file number to be duplicated in the source parameter. If the file number is already opened, the next highest available file number is used. The value passed must be within the legal range of file numbers. The default value for this parameter is zero (0).
Operation Notes | |
When a file descriptor is duplicated, the duplicate file descriptor shares the same data pointer as the original file descriptor in the same way that file descriptors share the same data pointer with MULTI access. This gives you the ability to perform operations on files that have not been previously available. Specifically, files that are opened for SHARED or EXCLUSIVE access can now have their data pointers shared among multiple file descriptors, at the discretion of the application that originally opens the file descriptor. Related Information | |
- Intrinsics
FOPEN, HPFOPEN - Commands
None - Manuals
None
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