HP 3000 Manuals HP 3000 Manuals
Chapter 8 Interfacing with Other Languages This chapter describes how to call routines written in HP Pascal/iX, HP COBOL/iX, or HP C/iX from an HP FORTRAN 77/iX program, and how to call an HP FORTRAN 77/iX subroutine or function from HP Pascal/iX, HP COBOL/iX, or HP C/iX. If you call other languages from HP FORTRAN 77/iX, the actual parameters of the internal procedure or function must match the formal parameters of the external procedure or function. The CHECK_ACTUAL_PARM compiler option determines the level of the checking information placed in the object file for the Link Editor when performing a LINK or ADDXL. Refer to the HP FORTRAN 77/iX Reference Manual for more information on the CHECK_ACTUAL_PARM compiler directive. When calling HP FORTRAN 77/iX from other languages, you must match the parameters appearing in the non-FORTRAN 77 program with the formal parameters of the external FORTRAN 77 procedure or function. The CHECK_FORMAL_PARM compiler option determines the checking information placed in the object file for the Link Editor when performing a LINK or ADDXL. Refer to the HP FORTRAN 77/iX Reference Manual for more information on the CHECK_FORMAL_PARM compiler option. All parameters passed to an HP FORTRAN 77/iX subprogram must be passed by reference. By default, HP FORTRAN 77/iX passes parameters of all types by reference, except for character data. When passing character data, a descriptor is passed that includes the address and length of the string. HP FORTRAN 77/iX allows parameters to be passed by value to invoke non-FORTRAN 77 program units that allow passing arguments by value. When passing parameters by value, the ALIAS compiler directive must indicate how each parameter is passed. HP FORTRAN 77/iX does not allow arrays to be passed by value. Therefore, an HP FORTRAN 77/iX program cannot call a non-FORTRAN 77 program unit that requires an array parameter to be passed by value. Also, when you call functions that have no parameters, you must specify an empty parameter list, ( ).