Write a Program to Replace all 0’s with 1’s in a Number.

replace.c

#include <stdio.h>
#include <math.h>

int main() {
    const int number = -102301;

    printf("before: %d\n", number);

    int input = number < 0 ? -number : number;
    int output = 0;
    int digits = 0;

    while (input > 0) {
        int last_digit = input % 10;
        input /= 10;

        if (last_digit == 0) {
            last_digit = 1;
        }

        output += last_digit * pow(10, digits);
        digits++;
    }

    if (number < 0) {
        output = -output;
    }

    printf("after:  %d\n", output);
}