COBOL Manual for TNS/E Programs (H06.03+)

Calling Other Programs and Routines
HP COBOL Manual for TNS/E Programs—520347-003
23-14
Restrictions on Calling Non-COBOL Routines
HP C Routines
An HP COBOL program must not call an HP C function that directly or indirectly
accesses the HP C function getenv.
An HP COBOL program indirectly calls HP C functions that allocate and deallocate
memory and perform HP C input-output operations. Do not directly call the HP C
function getenv from an HP COBOL program.
If a program has a COBOL MAIN program, and calls HP C or HP C++ functions that
perform HP C or HP C++ I/O operations on the standard files stdin, stdout, or
stderr, the HP C library function fopen_std_file must be called before any such
operations take place. You need fopen_std_file (0,x ) for input,
fopen_std_file (1,x ) for output, and fopen_std_file (2,x ) for the stderr.
This function must be called from an HP C or HP C++ routine. Also, the HP C program
must be compiled “with extensions” if you are going to call this function. See the
Guardian Native C Library Calls Reference Manual for more information on the
fopen_std_file function.
An HP COBOL program cannot call an HP C function that has these characteristics:
•
Has lowercase letters in its name, if the HP C function is called by ENTER (the
compiler upshifts them). This restriction does not apply to HP C functions called by
CALL.
•
Has a variable parameter list.
•
Returns a structured value.
•
Specifies a formal parameter whose type has no corresponding HP COBOL type
(to see which HP C types have corresponding HP COBOL types, see Appendix B,
Data Type Correspondence.
A TNS/E HP COBOL program and a TNS/E HP C program can share data under these
conditions:
•
Level-01 HP COBOL data items are described with the EXTERNAL clause.
•
HP C data names that the HP COBOL program references have no lowercase
letters or underscores.
•
If the HP COBOL and HP C programs are sharing strings, the strings end in the
zero byte that HP C expects.
In Example 23-2, the HP COBOL and HP C programs share the data item MYVAR.