Change int variable pointed by pointer

Question

I am a little bit newbie, and pointers still do troubles to me. I would like to change value of int, which I get from parameter (as a pointer) in function.

#include <stdio.h>

bool function(int* a){

    a++;

    printf("%d",*a); //getting some big number, maybe address. If i did not use a++; I get just normal a, unchanged.

    return false;
}

Answer 1

The problem is that you're incrementing the pointer (not the value pointed with it) in the statement a++. If you want to increment the value of the parameter, you should dereference it first:

(*a)++; //instead of a++;

Printf is not printing exactly an address, is just printing the value of the integer (may be an integer, can be something else) stored next to your parameter a.

Answer 2

You need to dereference the pointer to get the actual value of the integer (not address) by using *a. Then you can increment that value. So your code should be (*a)++ instead of a++ (In your case you are just incrementing the address and trying to access the next location in memory).