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

replace-0-with-1.c

#include <stdio.h>

int main() {
    int N = 102301;

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

    for (int power = 1; power <= N; power *= 10) { // 1, 10, 100, ...
        int digit = N / power % 10;

        if (digit == 0) {
            N += power; // replace 0 with 1 means add 1 * power
        }
    }

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