# 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.
Examples:

```    102 - 152
1020 - 1525 ```

Use of array to store all digits is not allowed.

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
#include<stdio.h>

// 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;
}```

Output:

`15125`