How to check if a number contains a certain digit?

Question

I need to write a boolean method called hasEight(), which takes an int as input and returns true if the number contains the digit 8 (e.g., 18, 808).

I don't want to use the "String conversion method".

I've tried the below code, but that only checks for the last digit.

import java.util.Scanner;

public class Verificare {

    public static boolean hasEight(int numarVerificat) {
        int rest = numarVerificat % 10;
        return rest == 8;
    } 

    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);
        System.out.print("Introduceti numarul pentru verificare: ");
        int numar = keyboard.nextInt();
        Verificare.hasEight(numar);
        System.out.println("Afirmatia este: " + Verificare.hasEight(numar));
    
        keyboard.close();
    }
}

Is this homework? If so, you might want to tag it as such, show us what you've tried so far, and explain where you're stuck. — Wander Nauta, Feb 02 '17 at 16:13
Possible duplicate of [How to get the separate digits of an int number?](http://stackoverflow.com/questions/3389264/how-to-get-the-separate-digits-of-an-int-number) — Uma Kanth, Feb 02 '17 at 16:14
What is the number `808`? Decimal right? So it's `8x10^2 + 0x10^1 + 8x10^0`. So; given that, how would you access each digit individually? — Boris the Spider, Feb 02 '17 at 16:15
Seems more like an IQ puzzle than relevant homework. When would one ever need to know how to do this? — jumps4fun, Feb 02 '17 at 16:20
@jsheeran no, it equals 0. `10^1 == 10`; `10 * 0 == 0`. Where did `17` come from? — Boris the Spider, Feb 02 '17 at 16:28
Welcome to stackoverflow! Please take a moment to review our [tour](http://stackoverflow.com/tour). — Tavrock, Feb 02 '17 at 17:05

score 11 · Accepted Answer · answered Feb 02 '17 at 16:21

11

If you don't want to use string conversion methods then i think this method can be used.

public bool hasEight(int number)
{
      while(number > 0)
      {
          if(number % 10 == 8)
              return true;

          number=number/10;
      }
      return false; 
}

answered Feb 02 '17 at 16:21

Uday

345
4
8

Thanks for your help. I used your advice Uday. – Sebastian Gruia Feb 02 '17 at 19:21

score 1 · Answer 2 · answered Feb 02 '17 at 16:29

Use the below function.

boolean hasEight(int num) {
    int rem;
    while (num > 0) {
        rem = num % 10;
        if (rem == 8)
            return true;
        num = num / 10;
    }
    return false;
}

In every iteration of the loop, last digit of the number is retrieved (remainder when divided by 10). If it is 8, true is returned. Else, number is divided by 10 (integer division so that last digit is removed) and another iteration is started. When all digits are checked (8 or not), number becomes 0 and loop stops.

Thanks for your help. I used your advice @Krisha Teja – Sebastian Gruia Feb 02 '17 at 19:22 — Sebastian Gruia, Feb 02 '17 at 19:22

score 1 · Answer 3 · answered Jul 13 '19 at 12:46

    public static boolean hasEight(int numarVerificat)
    {
        while(numarVerificat > 0)
          {
              if(numarVerificat % 10 == 8)
                  break;
              numarVerificat=numarVerificat/10;
          }
          return (numarVerificat>0); 
    }

How to check if a number contains a certain digit?

3 Answers3

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