finding intersection of arrays to find hcf

Question

The first function find factors of a number and works fine.

//first find divisors of a number

function divisors(n) {
    var result = [];
    for (var i = 1; i <= n; i++) {
      if ((n % i) == 0) {
        result.push(i);
      }
    }
    return result;
  }
  //the following gives problems

function commonTerms(arr1, arr2) {
  var arr1 = [];
  arr2 = [];
  common = [];
  var m = Math.min(arr1.length, arr2.length);
  for (var i = 0; i < arr1.length; i++) {
    for (var j = 0; j < arr2.length; j++) {
      if ((arr1(i)) == (arr2(j))) {
        common.push(arr1(i));
      } else {
        continue;
      }
    }
  }
  return common;
}

var x = parseInt(prompt("number to find divisors of?"));
document.write(divisors(x));
var y = parseInt(prompt("number to find divisors of?"));
document.write("<br>" + divisors(y));
alert(commonTerms(divisors(x), divisors(y)));

<!DOCTYPE html>
<html>

<head>
  <link href="css/styles.css" rel="stylesheet">
</head>

<body>

  <h1>GCD</h1>

  <p>This is my first website
    <br>finding div</p>
</body>

</html>

It won't return anything, the second function is the one giving me trouble. I have been looking at it for an hour. Starting to learn programming on my own. Thank you for your help.

Why are you redefining `var arr1 = []` inside function `commonTerms` — Rajesh, Jan 04 '16 at 11:33

score 2 · Accepted Answer · edited May 23 '17 at 12:00

2

The problem is that you're accessing array items like this: arr(i). You should do it with square brackets:

if ((arr1[i])==(arr2[j])){
      common.push(arr1[i]);
      //...
}

And you don't need the round braces at all. Plus you'd better use strict comparison (=== instead of ==).

So it would be:

if (arr1[i] === arr2[j]){
      common.push(arr1[i]);
      //...
}

BTW Consider checking this question

edited May 23 '17 at 12:00

Community

1
1

answered Jan 04 '16 at 11:35

Alexander Mikhalchenko

4,525
3
32
56

Thank you what a silly mistake!, I did check that question, although it is hard for me to understand other people coding yet... – Kepol Jan 04 '16 at 11:41

score 2 · Answer 2 · answered Jan 04 '16 at 11:40

2

First, if ((arr1[i])==(arr2[j])) instead of if ((arr1(i))==(arr2(j)))

Second, remove var arr1=[]; arr2 =[]; as they are received parameters, and leave var common=[]

I would also use m in the loop as I guess that was your intention

answered Jan 04 '16 at 11:40

guysigner

2,822
1
19
23

It was my intention until I realized I didn't need it :S – Kepol Jan 04 '16 at 11:42

score 1 · Answer 3 · answered Jan 04 '16 at 11:48

As I have already commented, you are resetting parameters and hence its not working. Check following code.

//first find divisors of a number

function divisors(n) {
    var result = [];
    for (var i = 1; i <= n; i++) {
      if ((n % i) == 0) {
        result.push(i);
      }
    }
    return result;
  }
  //the following gives problems

function commonTerms(arr1, arr2) {
  common = [];
  var m = Math.min(arr1.length, arr2.length);
  for (var i = 0; i < arr1.length; i++) {
    for (var j = 0; j < arr2.length; j++) {
      if ((arr1(i)) == (arr2(j))) {
        common.push(arr1(i));
      } else {
        continue;
      }
    }
  }
  return common;
}

var x = parseInt(prompt("number to find divisors of?"));
document.write(divisors(x));
var y = parseInt(prompt("number to find divisors of?"));
document.write("<br>" + divisors(y));
alert(commonTerms(divisors(x), divisors(y)));

<!DOCTYPE html>
<html>

<head>
  <link href="css/styles.css" rel="stylesheet">
</head>

<body>

  <h1>GCD</h1>

  <p>This is my first website
    <br>finding div</p>
</body>

</html>

Thank you I also didn't use square brackets with arrays – Kepol Jan 04 '16 at 11:49 — Kepol, Jan 04 '16 at 11:49
Yes! Saw @Alexander M. answer. – Rajesh Jan 04 '16 at 11:50 — Rajesh, Jan 04 '16 at 11:50

finding intersection of arrays to find hcf

3 Answers3