I want to initialize and then print the elements of a 2D array using javascript. I wrote this code but nothing displays as output. How to output this array?
var m = 6;
var n = 3;
var mat = new Array[m][n];
for (i = 0; i < mat.length; i++) {
for (j = 0; j < mat[i].length; j++) {
mat[i][j]) = i * j;
document.writeln(mat[i][j]);
}
document.writeln("<br />");
}
<html>
<body>
</body>
<script>
var m=6;
var n=3;
var mat =new Array(m);
for( var i=0; i < m ; i++){
mat[i] = new Array(n);
for( var j=0;j< n ;j++){
mat[i][j] = i*j;
document.writeln(mat[i][j]);
}
document.writeln("<br />");
}
</script>
</html>
As BenG pointed out, you've got an extra ) but you also aren't initializing your array correctly. Javascript doesn't allow you to declare multi-dimensional arrays like other languages. Instead, you'd have to do something more like this:
var m = 6;
var n = 3;
var mat = new Array(m);
for (var i = 0; i < m; i++) {
mat[i] = new Array(n);
}
Javascript arrays are dynamic. They will grow to the size you require. You can call push() to add a new element to the array. It's also worth noting that you should avoid using the new keyword with objects and arrays. Use their literal notations [] for arrays and {} for objects. So a better solution here would be to push to the arrays as you need them.
var mat = [];
var m = 6;
var n = 3;
for (var i = 0; i < m; i++) {
// Let's add an empty array to our main array
mat.push([]);
for (var j = 0; j < n; j++) {
mat[i].push(i * j);
document.writeln(i * j);
}
document.writeln('<br />');
}
var mat = [];and still get the results you'd like, as long as you change your loops accordingly