C telling me to initialize variable even though it's already initialized

Question

I am working on CS50 PSET1. I have the following code so far:

#include <stdio.h>
#include <cs50.h>

int main(void) {

    float change;

    do {
        printf("Change: ");
        change = get_float();
    } while(change < 0);

    int coins;

    for(int q = change; q < 25; q++) {
        q = 25 / q;
        coins += 1;
    }
    printf("%i", coins);

}

I am having an issue. When I try to compile my code with the make command I get an error saying this

greedy.c:17:9: error: variable 'coins' is uninitialized when used here [-> Werror,-Wuninitialized] coins += 1;

Answer 1

The compiler is correct. You never assign anything to coins in the first place. All you do is increment its (uninitialized) value.

To assign an initial value, write

int coins = 0;  /* or whatever the correct initial value is */

As an aside, I'm not quite sure what the intent is, but the following is highly unlikely to be what you want:

for(int q = change; q < 25; q++) {
    q = 25 / q;

Note how the assignment modifies the loop variable. While this is permissible, in this context it looks unlikely to be intentional.