Best Way to Check if a Number Contains Another Number

Need to find out if a number contains another number? And you want better performance than converting to a string and then looping through that to find the key number? Well you’ve come to the right place!

Using a combination of the modulo operator and division it’s possible to pull the number apart one digit at a time until it reaches 0.

Implementation Using a Loop

def checkNumberIfContainsKey(number, key):
    while number > 0:
        if number % 10 == key:
             return True
        number = number // 10
    return False

package main

import "fmt"

func checkNumberIfContainsKey(number, key int) bool {
	for number > 0 {
		if number%10 == key {
			return true
		}
		number = number / 10
	}
	return false
}

func main() {
	fmt.Println(checkNumberIfContainsKey(359, 9))
}

function checkNumberIfContainsKey(number, key){
    while(number > 0){
        if(number%10 == key){
            return true;
        }
        number = Math.floor(number / 10);        
    }
    return false;
}

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

bool checkNumberIfContainsKey(int number, int key)
{
	while (number > 0) 
	{
		if (number % 10 == key) 
		{
			return true;
		}
		number = number / 10;
	}
	return false;
}

int main(int argc, char const *argv[])
{
	cout << checkNumberIfContainsKey(359,9) << endl;
	return 0;
}

class ContainsKey {
    public static boolean checkNumberIfContainsKey(int num, int key) {
        while (num > 0) {
            if (num % 10 == key) {
                return true;
            }
            num = num / 10;
        }
        return false;
    }
}

Recursive Implementation

def checkNumberIfContainsKey(number, key):
    if number == 0:
        return False
    
    if number % 10 == key:
        return True
    
    return checkNumberIfContainsKey(number // 10, key)

package main

import "fmt"

func checkNumberIfContainsKey(number, key int) bool {
	if number == 0 {
		return false
	}
	if number%10 == key {
		return true
	}
	return checkNumberIfContainsKey(number / 10, key)
	
}

func main() {
	fmt.Println(checkNumberIfContainsKey(359, 9))
}

function checkNumberIfContainsKey(number, key){
    if (number === 0) {
    	return false;
    }
    if(number%10 == key) {
    	return true;
    }
    return checkNumberIfContainsKey(Math.floor(number / 10), key);
}

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

bool checkNumberIfContainsKey(int number, int key)
{
	while (number > 0) 
	{
		if (number % 10 == key) 
		{
			return true;
		}
		number = number / 10;
	}
	return false;
}

int main(int argc, char const *argv[])
{
	cout << checkNumberIfContainsKey(359,9) << endl;
	return 0;
}

class ContainsKey {
    public static boolean checkNumberIfContainsKey(int num, int key) {
        if (num == 0) {
            return false;
        }

        if (num % 10 == key) {
            return true;
        }

        return checkNumberIfContainsKey(num / 10, key);
    }
}