// just needed so you actually can compile this with gcc
typedef unsigned long uint64_t;
// for passing an argument and receiving a return value
uint64_t arg;
void
factorial()
{
uint64_t n;
n = arg;
arg = n-1;
if (arg == 0) {
arg = 1;
} else {
factorial();
arg = arg * n;
}
}
void
getui()
{
// implementation of subprogram getui
scanf("%lu", &arg);
}
void
puts()
{
// implementation of subprogram puts
printf("%s", arg);
}
void
putui()
{
// implementation of subprogram putui
printf("%lu", arg);
}
// some string literals
char msg0[] = "n = ";
char msg1[] = "! = ";
void
main()
{
// local variable
uint64_t n;
// copy pointer to string literal to arg, call puts
arg = msg0;
puts();
// call subprogram getui, copy return value to local variable
getui();
n = arg;
// copy local variable to arg, call putui
arg = n; // could be "optimized away"
putui();
// copy pointer to string literal to arg, call puts
arg = msg1;
puts();
// copy local n to global arg, call subprogram factorial
arg = n;
factorial();
// copy local variable to arg, call putui
//arg = n;
putui();
// for convenience
putchar('\n');
}