Replace all ‘0’ with ‘5’ in an input Integer

Given a integer as a input and replace all the ‘0’ with ‘5’ in the integer.

    102 - 152
    1020 - 1525 

Use of array to store all digits is not allowed.

Source: Amazon interview Experience | Set 136 (For SDE-T)

We strongly recommend to minimize the browser and try this yourself first.
The idea is simple, we get the last digit using mod operator ‘%’. If the digit is 0, we replace it with 5, otherwise keep it as it is. Then we recur for remaining digits.

Following is C implementation of the above idea.

// C program to replace all ‘0’ with ‘5’ in an input Integer

// A recursive function to replace all 0s with 5s in an input number
// It doesn't work if input number itself is 0.
int convert0To5Rec(int num)
    // Base case for recursion termination
    if (num == 0)
        return 0;

    // Extraxt the last digit and change it if needed
    int digit = num % 10;
    if (digit == 0)
        digit = 5;

    // Convert remaining digits and append the last digit
    return convert0To5Rec(num/10) * 10 + digit;

// It handles 0 and calls convert0To5Rec() for other numbers
int convert0To5(int num)
    if (num == 0)
       return 5;
    else return  convert0To5Rec(num);

// Driver program to test above function
int main()
    int num = 10120;
    printf("%d", convert0To5(num));
    return 0;



This article is contributed by Sai Kiran. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

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