pointer.c

#include <stdio.h>

void update(int* variable)
{
  *variable = *variable * 2;
}

int main(int, char**)
{
  int a = 1;
  int b = 2;
  int c = 3;
  
  printf("a = %d, b = %d, c = %d\n", a, b, c);
  update(&a);
  update(&b);
  update(&c);
  printf("a = %d, b = %d, c = %d\n", a, b, c);
  
  return 0;
}