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Which to Use: HPFOPEN or FOPEN The HPFOPEN intrinsic is the recommended intrinsic for creating and opening files on an MPE/iX-based computer system. HPFOPEN is designed to be more flexible and extendible than the FOPEN intrinsic. In addition, HPFOPEN's available options are a superset of the options available through FOPEN. For example, mapped access is available through HPFOPEN but not through FOPEN.
NOTE One HPFOPEN option, the file privilege option, when used to set a new file's privilege level to other than 3 (least-privileged, or user level), disallows all subsequent access of that file by the FOPEN intrinsic. (For compatibility reasons, FOPEN can only access a file whose file privilege level is three.)
You should use the FOPEN intrinsic only if you are planning to migrate your application between MPE/iX-based systems and MPE V/E-based systems. HPFOPEN is not supported on an MPE V/E-based system. The examples in this chapter illustrate the use of the HPFOPEN intrinsic. The HPFOPEN intrinsic uses an itemnum, item pair convention for optional parameter passing. The itemnum and item parameters are paired, where the nth itemnum is immediately followed in the parameter list by the nth item. The itemnum parameter passes by value an integer that the intrinsic uses to define the meaning and expected data type of the value passed by reference in the corresponding item parameter. For details on HPFOPEN and FOPEN parameters, refer to the respective intrinsics descriptions in the MPE/iX Intrinsics Reference Manual (32650-90028).