# 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 ` `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 ` `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 `

Output:

```4
```

Time Complexity: O(N), where N is the length of the number.

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