Question

125

how to compare two arrays of different length if you dont know the length of each one in javascript?

rated 0 times [ 127] [ 2] / answers: 1 / hits: 19789 / 13 Years ago, fri, november 18, 2011, 12:00:00

I am stuck in this. I got 2 arrays, I don't know the length of each one, they can be the same length or no, I don't know, but I need to create a new array with the numbers no common in just a (2, 10).

For this case:

    var a = [2,4,10];

    var b = [1,4];



    var newArray = [];



    if(a.length >= b.length ){

        for(var i =0; i < a.length; i++){

            for(var j =0; j < b.length; j++){

                if(a[i] !=b [j]){

                    newArray.push(b);        

                }        

            }

        }

    }else{}

I don't know why my code never reach the first condition and I don't know what to do when b has more length than a.

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denis

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3 Years ago

answered 13 Years ago zahrafrancisr · Accepted Answer

It seems that you have a logic error in your code, if I am understanding your requirements correctly.

This code will put all elements that are in a that are not in b, into newArray.

var a = [2, 4, 10];

var b = [1, 4];



var newArray = [];



for (var i = 0; i < a.length; i++) {

    // we want to know if a[i] is found in b

    var match = false; // we haven't found it yet

    for (var j = 0; j < b.length; j++) {

        if (a[i] == b[j]) {

            // we have found a[i] in b, so we can stop searching

            match = true;

            break;

        }

        // if we never find a[i] in b, the for loop will simply end,

        // and match will remain false

    }

    // add a[i] to newArray only if we didn't find a match.

    if (!match) {

        newArray.push(a[i]);

    }

}

To clarify, if

a = [2, 4, 10];

b = [4, 3, 11, 12];

then newArray will be [2,10]