1.12. POINTERS
So we use pointers: probably, there is no better way to solve this task without them.
1.12.2 Returning values.
Pointers are often used to return values from functions (recallscanf()case (1.9 on page 66)).
For example, when a function needs to return two values.
Global variables example
#include <stdio.h>
void f1 (int x, int y, int sum, int product)
{
sum=x+y;
product=x*y;
};
int sum, product;
void main()
{
f1(123, 456, &sum, &product);
printf ("sum=%d, product=%d\n", sum, product);
};
This compiles to:
Listing 1.100: Optimizing MSVC 2010 (/Ob0)COMM _product:DWORD
COMM _sum:DWORD
$SG2803 DB 'sum=%d, product=%d', 0aH, 00H
_x$ = 8 ; size = 4
_y$ = 12 ; size = 4
_sum$ = 16 ; size = 4
_product$ = 20 ; size = 4
_f1 PROC
mov ecx, DWORD PTR _y$[esp-4]
mov eax, DWORD PTR _x$[esp-4]
lea edx, DWORD PTR [eax+ecx]
imul eax, ecx
mov ecx, DWORD PTR _product$[esp-4]
push esi
mov esi, DWORD PTR _sum$[esp]
mov DWORD PTR [esi], edx
mov DWORD PTR [ecx], eax
pop esi
ret 0
_f1 ENDP
_main PROC
push OFFSET _product
push OFFSET _sum
push 456 ; 000001c8H
push 123 ; 0000007bH
call _f1
mov eax, DWORD PTR _product
mov ecx, DWORD PTR _sum
push eax
push ecx
push OFFSET $SG2803
call DWORD PTR impprintf
add esp, 28
xor eax, eax
ret 0