HP SunSoft Pascal 4.0 - Manual (Page 139)

The C–Pascal Interface 115
6
Function Return Values
Function return values match types the same as with parameters, and they
pass in much the same way.
Simple Types
The simple types pass in a straightforward way, as follows:
The commands to compile and
execute
ChrCAVal.p and
ChrCAValMain.c with
-calign
hostname% pc -c -calign ChrCAVal.p
hostname% cc ChrCAVal.o ChrCAValMain.c -lpc
hostname% a.out
This is a string
The Pascal function,
RetReal.p
function RetReal(x: real): real;
begin
RetReal := x + 1.0
end; { RetReal }
The C main program,
RetRealMain.c
#include <stdio.h>
extern double RetReal(double);
int main(void)
{
double r, s;
r = 2.0;
s = RetReal(r);
printf(" %f \n", s);
}