Creating then printing 2D array - print problem

Question

I've got 2 functions. One to create 2D array, the other to print it. Something is wrong with the creating function, because when I create and send an 2D array by myself, everything is fine. But when I try to do this through the create funcion, the console is empty (but no errors). Could you help me?

function print2DArray (array2D) {
    for (var i = 0; i < array2D.length; i++) {
        for (var j = 0; j < array2D[i].length; j++) {
            console.log(array2D[i][j]);
        }
    }
}

function create2DArray (rows, columns) {
    var array2D = [];
    for (var i = 0, x = 0; i < rows; i++, x++) {
        array2D[i] = x;
        for (var j = 0; j < columns; j++) {
            x++;
            array2D.push(x);
        }
    }
    return array2D;
}

/*                 ← Here everything is fine
var arr = [
    [11, 12],
    [42, 2],
    [-4, -120],
    [0, 0],
    [1, 34],
];

print2DArray(arr);
 */

print2DArray(create2DArray(2, 3));       ← Empty console

Aalexander · Accepted Answer · 2021-01-21 08:57:22Z

The problem is that you don't create a 2D array as far more a 1D array.

In each iteration step you have to create an array and push it to your array to create a 2D one.

function print2DArray (array2D) {
    for (var i = 0; i < array2D.length; i++) {
        for (var j = 0; j < array2D[i].length; j++) {
            console.log(array2D[i][j]);
        }
    }
}

function create2DArray(rows, columns) {
    var array2D = [];
    
    for (var i = 0; i < rows; i++) {
        let temp = [];
        for (var j = 0; j < columns; j++) {
                temp[j] = Math.floor(Math.random() * Math.floor(100))
        }
        array2D.push(temp);
    }
    return array2D;
}

/*                 ← Here everything is fine
var arr = [
    [11, 12],
    [42, 2],
    [-4, -120],
    [0, 0],
    [1, 34],
];

print2DArray(arr);
 */

print2DArray(create2DArray(2, 3));       //← Empty console

Rajesh Kumaran · Accepted Answer · 2021-01-21 08:58:04Z

You have created an single dimension array which is why its going into the 2nd loop.

function print2DArray (array2D) {
   // console.log(array2D)
    for (var i = 0; i < array2D.length; i++) {
        for (var j = 0; j < array2D[i].length; j++) {
            console.log(array2D[i][j]);
        }
    }
}

function create2DArray (rows, columns) {
    var array2D = [];
    for (var i = 0, x = 0; i < rows; i++, x++) {
        array2D[i] = []
        for (var j = 0; j < columns; j++) {
            
            array2D[i].push(x);
            x++;
        }
    }
    return array2D;
}

/*                 ← Here everything is fine
var arr = [
    [11, 12],
    [42, 2],
    [-4, -120],
    [0, 0],
    [1, 34],
];

print2DArray(arr);
 */

print2DArray(create2DArray(2, 3));

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