c++ if statement not showing the answer correctly [on hold]

I'm a complete beginner coder. I've got an exercise and i don't seem to be able to finish it, whenever i try to get an answer with an if statement it doens't show it corretly and since I'm so new i can't figure it out, have been trying for over 4hrs.

#include <iostream>

using namespace std;

int main()
{
    long int x, a, b, c, e, f;
    long int d=10;

    cout << "enter a number" << endl;
    cin >> x;

    c=x%10;
    cout << c << endl;
    if (c=0)
        cout << "your number has 0's" << endl;
    else{
        while ((e!=0) && (f!=0)){
            e=x/d;
            f=e%10;
            d=d*10;
        }
        cout << "5  " << f << ";  " << e << endl;
        if (f=0)
            cout << "you have 0's" << endl;
        else 
            cout << "you have no 0's" << endl;
    }
    return 0;
}       

this is the code, the task is to find if a user input number has any 0's in it and so whenever you put in a number like 5480321 even tho it has an 0 and the cout<