Write a program in C to count the digits of a given number using recursion. Input: Input a non-negtive integer n. Output: Print the number of digits in the number n. Input Sample: 50 Output Sample: The number of digits in 50 is: 2

Sure, here's a program in C that counts the digits of a given number using recursion:

#include <stdio.h>

// Function to count the number of digits in a number using recursion
int countDigits(int n) {
    if (n == 0) {
        return 0;
    } else {
        return 1 + countDigits(n / 10);
    }
}

int main() {
    int n;

    // Read input from user
    printf("Enter a non-negative integer: ");
    scanf("%d", &n);

    // Count the number of digits using recursion
    int numDigits = countDigits(n);

    // Print the result
    printf("The number of digits in %d is: %d\n", n, numDigits);

    return 0;
}

The `countDigits()` function takes an integer `n` as input and recursively counts the number of digits in `n` by dividing it by 10 until `n` becomes 0. The base case is when `n` is 0, in which case the function returns 0. Otherwise, the function returns 1 plus the result of calling itself with `n/10`.

In the `main()` function, we read the input from the user, call the `countDigits()` function to count the number of digits, and print the result.