Best way to check if a number contains another number

Question

For example if the number 752 contains the number 5? Whats the best way to check? Convert to string or divide into individual digits?

looking for a number in a number - string ... looking for a digit in a number - string or individual digits — Jaromanda X, Jul 29 '15 at 14:17
I would convert it to a string, and do a regex match on it: `(752).toString().match(/5/)` — ndugger, Jul 29 '15 at 14:18
possible duplicate of [Check if a string contains a specific number in JavaScript](http://stackoverflow.com/questions/13372958/check-if-a-string-contains-a-specific-number-in-javascript) — Liam, Jul 29 '15 at 14:20
if none of the answers worked or you are still facing trouble let me know so I can help — AmmarCSE, Jul 30 '15 at 00:32

AmmarCSE · Accepted Answer · 2015-07-29T14:23:01.233

20

Convert to string and use indexOf

(752+'').indexOf('5') > -1

console.log((752+'').indexOf('5') > -1);
console.log((752+'').indexOf('9') > -1);

edited Jul 29 '15 at 14:23

answered Jul 29 '15 at 14:19

AmmarCSE

30,079
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2

The `.` operator has higher precedence than `+`, so you need parentheses for this to really work. – Pointy Jul 29 '15 at 14:22
2

You have a problem in your operator precedence. It should be `(752+'').indexOf('5')`, otherwise `''.indexOf('5')` will evaluate first. – BoppreH Jul 29 '15 at 14:22
2

A Regex would also be an order of magnitude less efficent @Nick – Liam Jul 29 '15 at 14:23

score 3 · Answer 2 · answered Feb 05 '20 at 09:12

3

Convert to string and use one of these options:

indexOf():

(number + '').indexOf(needle) > -1;

includes():

(number + '').includes(needle);

answered Feb 05 '20 at 09:12

Halfacht

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score 1 · Answer 3 · edited Jul 29 '15 at 15:06

1

You can use 3 ways:

Check it by string contains:

var num = 752;
num.toString().indexOf('5') > -1 //return true or false - contains or not

Check by loop

var f = 2;
while(num > 0 ){
  if( num % 10 == f){
    console.log("true");
    break;
  }
  num = Math.floor(num / 10); 
}

Check by regular expressions

 num.toString().match(/5/) != null //return true if contains

edited Jul 29 '15 at 15:06

gen_Eric

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answered Jul 29 '15 at 14:45

RAZVOR

55
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7

score 0 · Answer 4 · answered May 04 '19 at 11:52

function checkNumberIfContainsKey(number, key){
    while(number > 0){
        if(number%10 == key){
            return true;
        }
        number = Math.trunc(number / 10);        
    }
    return false;
}
console.log(
  checkNumberIfContainsKey(19, 9),   //true
  checkNumberIfContainsKey(191, 9),  //true
  checkNumberIfContainsKey(912, 9),  //true
  checkNumberIfContainsKey(185, 9)  //false
);

The most efficient solution among available answers because of the complexity of this program is just O(number of digits) if number = 10235 then the number of digits = 5

score 0 · Answer 5 · answered Oct 23 '19 at 09:56

You can also use "some" function. "Some"thing like this:

    function hasFive(num){
         return num.toString().split("").some(function(item){
          return item === "5";
         }); 
    }

and then you can call it:

   hasFive(752)

Further improved is that you make a function that takes number and digit you want to check:

       function hasNumber(num, digit){
             return num.toString().split("").some(function(item){
                 return item == digit;
             }); 
        }

And then call it in similar way:

hasNumber(1234,3) //true
hasNumber(1244,3) //false

So that way we can check any number for any digit. I hope so "some"one will find this useful. :)

Best way to check if a number contains another number

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