Count of Prime digits in a Number

Given an integer N, the task is to count the number of prime digits in N.
Examples:

Input: N = 12 
Output: 1 
Explanation:
Digits of the number – {1, 2} 
But, only 2 is prime number.
Input: N = 1032 
Output: 2 
Explanation:
Digits of the number – {1, 0, 3, 2} 
3 and 2 are prime number 

Approach: The idea is to iterate through all the digits of the number and check whether the digit is a prime or not. Since there are only four possible prime numbers in the range [0, 9] and every digit for sure lies in this range, we only need to check the number of digits equal to either of the elements in the set {2, 3, 5, 7}. 
Below is the implementation of this approach: 

CPP

// C++ program to count the number of
// prime digits in a number

#include <bits/stdc++.h>
using namespace std;

// Function to find the count of
// prime digits in a number
int countDigit(int n)
{
    int temp = n, count = 0;

    // Loop to compute all the digits
    // of the number
    while (temp != 0) {

        // Finding every digit of the
        // given number
        int d = temp % 10;

        temp /= 10;

        // Checking if digit is prime or not
        // Only 2, 3, 5 and 7 are prime
        // one-digit number
        if (d == 2 || d == 3
            || d == 5 || d == 7)
            count++;
    }

    return count;
}

// Driver code
int main()
{
    int n = 1234567890;

    cout << countDigit(n) << endl;
    return 0;
}

Java

// Java program to count the number of
// prime digits in a number
import java.util.*;
import java.io.*;
class GFG {

    // Function to find the count of
    // prime digits in a number
    static int countDigit(int n)
    {
        int temp = n, count = 0;

        // Loop to compute all the digits
        // of the number
        while (temp != 0) {

            // Finding every digit of the
            // given number
            int d = temp % 10;

            temp /= 10;

            // Checking if digit is prime or not
            // Only 2, 3, 5 and 7 are prime
            // one-digit number
            if (d == 2 || d == 3
                || d == 5 || d == 7)
                count++;
        }

        return count;
    }

    // Driver code
    public static void main (String[] args)
    {
        int n = 1234567890;

        System.out.println(countDigit(n)) ;

    }
}

// This code is contributed by AnkitRai01

Python3

# Python3 program to count the number of
# prime digits in a number

# Function to find the count of
# prime digits in a number
def countDigit(n):
    temp = n
    count = 0

    # Loop to compute all the digits
    # of the number
    while (temp != 0):

        # Finding every digit of the
        # given number
        d = temp % 10

        temp //= 10

        # Checking if digit is prime or not
        # Only 2, 3, 5 and 7 are prime
        # one-digit number
        if (d == 2 or d == 3 or d == 5 or d == 7):
            count += 1

    return count

# Driver code
if __name__ == '__main__':
    n = 1234567890

    print(countDigit(n))

# This code is contributed by mohit kumar 29

C#

// C# program to count the number of
// prime digits in a number
using System;

class GFG {

    // Function to find the count of
    // prime digits in a number
    static int countDigit(int n)
    {
        int temp = n, count = 0;

        // Loop to compute all the digits
        // of the number
        while (temp != 0) {

            // Finding every digit of the
            // given number
            int d = temp % 10;

            temp /= 10;

            // Checking if digit is prime or not
            // Only 2, 3, 5 and 7 are prime
            // one-digit number
            if (d == 2 || d == 3
                || d == 5 || d == 7)
                count++;
        }

        return count;
    }

    // Driver code
    public static void Main (string[] args)
    {
        int n = 1234567890;

        Console.WriteLine(countDigit(n)) ;
    }
}

// This code is contributed by AnkitRai01

Javascript

<script>

// JavaScript program to count the number of
// prime digits in a number


// Function to find the count of
// prime digits in a number
function countDigit(n)
{
    let temp = n, count = 0;

    // Loop to compute all the digits
    // of the number
    while (temp != 0) {

        // Finding every digit of the
        // given number
        let d = temp % 10;

        temp = Math.floor(temp / 10);

        // Checking if digit is prime or not
        // Only 2, 3, 5 and 7 are prime
        // one-digit number
        if (d == 2 || d == 3
            || d == 5 || d == 7)
            count++;
    }

    return count;
}

// Driver code

let n = 1234567890;

document.write(countDigit(n) + "<br>");

// This code is contributed by gfgking


</script>

Output:

4

Time Complexity: O(log₁₀N), where N is the length of the number.
Auxiliary Space: O(1)

Method#2:Use Recursion

C++

// C++ program to count the number of
// prime digits in a number

#include <bits/stdc++.h>
using namespace std;

// Function to find the count of
// prime digits in a number
int countDigit(int n,int count=0)
{
    //BASE CASE
    if (n==0)
        return count;

    // Finding every digit of the
    // given number
    int d = n % 10;
    n /= 10;

    // Checking if digit is prime or not
    // Only 2, 3, 5 and 7 are prime
    // one-digit number
    if (d == 2 || d == 3|| d == 5 || d == 7){count++;}

    countDigit(n,count);//recursively calling function
}

// Driver code
int main()
{
    int n = 1234567890;

    cout << countDigit(n) << endl;
    return 0;
}
//This code is contributed by Shivesh Kumar Dwivedi

Java

// Java program to count the number of
// prime digits in a number
import java.util.*;
import java.io.*;
class GFG
{

    // Function to find the count of
    // prime digits in a number
    static int countDigit(int n, int count)
    {
        // BASE CASE
        if (n == 0)
            return count;

        // Finding every digit of the
        // given number
        int d = n % 10;
        n /= 10;

        // Checking if digit is prime or not
        // Only 2, 3, 5 and 7 are prime
        // one-digit number
        if (d == 2 || d == 3 || d == 5 || d == 7) {
            count++;
        }

        return countDigit(n, count);
        // recursively calling function
    }

    // Driver code
    public static void main(String[] args)
    {
        int n = 1234567890;

        System.out.println(countDigit(n, 0));
    }
}

// This code is contributed by phasing17

Python3

# Python3 program to count the number of
# prime digits in a number

# Function to find the count of
# prime digits in a number
def countDigit(n, count = 0):

    # BASE CASE
    if (n == 0):

        print(count)
        return;

    # Finding every digit of the
    # given number
    d = n % 10;
    n = int(n / 10);

    # Checking if digit is prime or not
    # Only 2, 3, 5 and 7 are prime
    # one-digit number
    if (d == 2 or d == 3 or d == 5 or d == 7):
        count += 1

    countDigit(n, count);#recursively calling function

# Driver code
n = 1234567890;
countDigit(n)

# This code is contributed by phasing17

C#

// C# program to count the number of
// prime digits in a number

using System;
using System.Collections.Generic;

class GFG {
  // Function to find the count of
  // prime digits in a number
  static int countDigit(int n, int count = 0)
  {
    // BASE CASE
    if (n == 0)
      return count;

    // Finding every digit of the
    // given number
    int d = n % 10;
    n /= 10;

    // Checking if digit is prime or not
    // Only 2, 3, 5 and 7 are prime
    // one-digit number
    if (d == 2 || d == 3 || d == 5 || d == 7) {
      count++;
    }

    return countDigit(n, count);
    // recursively calling function
  }

  // Driver code
  public static void Main(string[] args)
  {
    int n = 1234567890;

    Console.WriteLine(countDigit(n));
  }
}

// This code is contributed by phasing17

Javascript

// JS program to count the number of
// prime digits in a number

// Function to find the count of
// prime digits in a number
function countDigit(n, count = 0)
{
    // BASE CASE
    if (n == 0)
    {
        console.log(count);
        return;
    }

    // Finding every digit of the
    // given number
    let d = n % 10;
    n = Math.floor(n / 10);

    // Checking if digit is prime or not
    // Only 2, 3, 5 and 7 are prime
    // one-digit number
    if (d == 2 || d == 3|| d == 5 || d == 7)
    {
        count++;
    }

    countDigit(n,count);//recursively calling function
}

// Driver code
let n = 1234567890;
countDigit(n)

// This code is contributed by phasing17

Output

4