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 />');
}
Related
I want to create multiple arrays that contain the same basic layout. Currently, i have
Array(10); //base array with moving blocks
for(var i = 0; i < 10; i++){ //creating an array within an array (2d)
base[i] = new Array(22);
}
var background = new Array(10); //background array with stationary blocks
for(var z = 0; z < 10; z++){ //same as before
background[z] = new Array(22);
}
var nextBlock = new Array(10); //next block array
for(var i = 0; i <10; i++){
nextBlock[i] = new Array(22);
}
and would like to have something similar to:
function arrayCreator(rows,cols){
var array = newArray(rows);
for(var i = 0;i < rows;i++){
array[i] = newArray(cols);
}
}
var base = arrayCreator(10,22);
var background = arrayCreator(10,22);
var nextBlock = arrayCreator(10,22);
but cant get it working. How should I approach this?
Looks like you forgot the return statement.
function arrayCreator(rows,cols){
var array = newArray(rows);
for(var i = 0;i < rows;i++){
array[i] = newArray(cols);
}
return array;
}
I want to create a multidimensional array like this:
array[0][1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]
array[1][21,22,23,24,25,26,27....]
array[.][....]
How can I do this in Javascript?
I have tried this:
var squares = new Array();
for(var i = 1; i <= 8; i++)
{
for(var j = 1; j <= 20; j++)
{
squares.push(i, j);
}
}
How can I accomplish this?
You can do something like this:
var squares = new Array();
for(var i = 0; i <= 8; i++)
{
squares[i] = new Array();
for(var j = (i * 20) + 1; j <= 20 * i + 20; j++)
if (squares[i] == null)
squares[i] = j;
else
squares[i].push(j);
}
Output comes like:
array[0][1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]
array[1][21,22,23,24,25,26,27....]
var array = []; // Main array
var numArrays = 10, // Number of sub-arrays
numPerArray = 20; // Number of squares per sub-array
for(var i = 0; i < numArrays; i++){
var subArray = [];
// Number to start at
var start = i * numPerArray;
// Count up to start + numPerArray
for(var j = start; j < start + numPerArray; j++){
subArray.push(j);
}
// Add to main array
array.push(subArray);
}
Use modulus operand to limit the inner array's size
var limit = 80
var inner_limit = 20
var square=[]
var inner =[]
for(var i=1;i<=limit;i++){
inner.push(i)
if(i%inner_limit==0){
square.push(inner)
inner = []
}
}
You can do it with two "for" loops. In the first loop you go through the main array and for each element add the elements from the second loop.
var arrayLength = 10; // Main array length
var limit = 20; // Number of squares
var array = [];
for ( var i = 0; i < arrayLength; i++ )
{
array[i] = []; // Create subArray
for( var j = 1; j <= limit; j++ )
{
array[i].push(j);
}
}
Here's a pseudocode example about what I'm trying to do:
var totalLanguages = XX;
for(var i = 0; i < totalLanguages; i++){
var dynamicArray + i = new Array();
/*.....*/
}
I need to create dynamically many arrays as the value of totalLanguages which can be either number.
This is to be able to do something like this:
for(var i = 0; i < totalLanguages; i++){
var arrayLanguages["es"] = dynamicArray+i;
var arrayLanguages["en"] = dynamicArray+i;
}
Is there any way to do this?
var languageNames = ['en', 'es'];
var languages = {};
for (var i = 0; i < languageNames.length; i++) {
languages[languageNames[i]] = [];
}
You are basically trying to recreate an array with variable names. Just use an Array to start out!
var dynamicArray = [];
for(var i = 0; i < totalLanguages; i++) {
dynamicArray[i] = new Array();
}
You can use multi-dimensional arrays:
var languagesArray = new Array(totalLanguages);
for(var i = 0; i < totalLanguages; i++) {
var innerArray = new Array();
innerArray.push("Hello");
innerArray.push("World");
languagesArray[i] = innerArray;
}
console.log(languagesArray[0][0]);
See: How can I create a two dimensional array in JavaScript?
How about:
for(var i = 0; i < totalLanguages; i++){
window["dynamicvariable " + i] = new Array();
/*.....*/
}
I have a table with numbers but they are stored as string so I am trying to use the function parseFloat to convert it into a table of ints. However, no matter how I do the for loops it gives me a blank table. I can parse the row and it will give me a single int. I can parse a single int as well but cant seem to parse a row or the table. here is what I have so far. This is just trying to convert one row. I tried two for loops for the entire table but that didn't work either. thanks.
var c =[];
var entries = $.parseJSON('<?php print(json_encode($try, true)); ?>');
for (var j = 0; j < 12; j++)
{
for (var i = 0; i < 7; i++)
{
c [j][i] = parseFloat(entries[j][i]);
}
}
alert(c);
here is entries json encodes [["-248","-163","-455","-1413","-1294","-1296","-1089"],["-172","-219","-1186","-1368","-1480","-1079","-845"],["-98","-198","-703","-996","-1100","-585","-616"],["-116","-241","-498","-642","-704","-354","-430"],["-137","-117","-264","-525","-533","-269","-476"],["-12","87","-257","-463","-551","-302","-535"],["170","61","-250","-472","-659","-220","-605"],["159","96","-234","-513","-617","-196","-710"],["185","117","-272","-521","-610","-258","-798"],["208","95","-234","-534","-696","-280","-854"],["192","151","-188","-641","-739","-279","-957"],["249","223","-235","-684","-763","-339","-978"]]
You have to initialize the second dimension of your array to also be an array. As it stands now, c[j] is just a single value so you can't do c[j][i] on it. There is also an error in your first for loop where you need to compare the value of j, not i. See this fixed code:
var c = [];
var entries = $.parseJSON('<?php print(json_encode($try, true)); ?>');
for (var j = 0; j < 12; j++)
{
c[j] = [];
for (var i = 0; i < 7; i++)
{
c [j][i] = parseFloat(entries[j][i]);
}
}
alert(c);
In your first loop for (var j = 0; i < 12; j++), you are using i for iteration but it is undefined and it should be j instead of i
var c =[];
var entries = $.parseJSON('<?php print(json_encode($try, true)); ?>');
for (var j = 0; j < entries.length ; j++)
{
c[j] = [];
for (var i = 0; i < entries[i].length ; i++)
{
c [j][i] = parseFloat(entries[j][i]);
}
}
function split(str)
{
var array = str.split(';');
var test[][] = new Array();
for(var i = 0; i < array.length; i++)
{
var arr = array[i].split(',');
for(var j = 0; j < arr.length; j++)
{
test[i][j]=arr[j];
}
}
}
onchange="split('1,2,3;4,5,6;7,8,9;a,b,c;d,e,f;g,h,i')"
it was not working. i need to split this string to 6*3 multi dimentional array
var array[][] = new Array() is not valid syntax for declaring arrays. Javascript arrays are one dimensional leaving you to nest them. Which means you need to insert a new array into each slot yourself before you can start appending to it.
Like this: http://jsfiddle.net/Squeegy/ShWGB/
function split(str) {
var lines = str.split(';');
var test = [];
for(var i = 0; i < lines.length; i++) {
if (typeof test[i] === 'undefined') {
test[i] = [];
}
var line = lines[i].split(',');
for(var j = 0; j < line.length; j++) {
test[i][j] = line[j];
}
}
return test;
}
console.log(split('a,b,c;d,e,f'));
var test[][] is an invalid javascript syntax.
To create a 2D array, which is an array of array, just declare your array and push arrays into it.
Something like this:
var myArr = new Array(10);
for (var i = 0; i < 10; i++) {
myArr[i] = new Array(20);
}
I'll let you apply this to your problem. Also, I don't like the name of your function, try to use something different from the standards, to avoid confusion when you read your code days or months from now.
function split(str)
{
var array = str.split(';'),
length = array.length;
for (var i = 0; i < length; i++) array[i] = array[i].split(',');
return array;
}
Here's the fiddle: http://jsfiddle.net/AbXNk/
var str='1,2,3;4,5,6;7,8,9;a,b,c;d,e,f;g,h,i';
var arr=str.split(";");
for(var i=0;i<arr.length;i++)arr[i]=arr[i].split(",");
Now arr is an array with 6 elements and each element contain array with 3 elements.
Accessing element:
alert(arr[4][2]); // letter "f" displayed