FUNCTION-POINTER phrase
The FUNCTION-POINTER phrase defines an item as a function-pointer
data item. A function-pointer data item can contain the address
of a descriptor for a procedure entry point.
A function-pointer is a 4-byte elementary item. Function-pointers have the same capabilities as procedure-pointers, but are 4 bytes in length instead of 8 bytes. Function-pointers are thus more easily interoperable with C function pointers.
A function-pointer can point to a function descriptor for one of the following
or
can contain NULL:
- The primary entry point of a COBOL program, defined by the PROGRAM-ID paragraph of the outermost program
- An alternate entry point of a COBOL program, defined by a COBOL ENTRY statement
- An entry point in a non-COBOL program
A VALUE clause for a function-pointer data item can contain only NULL or NULLS.
The GLOBAL, EXTERNAL,
OCCURS and VOLATILE clauses can be used with USAGE IS FUNCTION-POINTER.
A function-pointer can be used in the same contexts as a procedure-pointer, as defined in PROCEDURE-POINTER phrase.