I am trying to rotate a 2dimensional array in javascript
the code outside the forloop to switch the values works but when i try to do that inside the for loop the variables are not changing
i think it is some sort of reference problem and i searched for that but i can't find a solution to this problem
temp = tempboard[0][1];
console.log("unchanged:"+tempboard[0][1]+""+tempboard[6][1]);
tempboard[0][1] = tempboard[6][1];
tempboard[6][1] = temp;
console.log("changed:"+tempboard[0][1]+""+tempboard[6][1]);
for(i = 0; i < board.length; i++){
for(j = 0; j < board[0].length; j++){
/*a = tempboard[i][j];
b = tempboard[j][i];
temp = a;
a = b;
b = temp;
console.log(a+" "+b);*/
temp = tempboard[i][j];
console.log("unchanged:"+tempboard[i][j]+""+tempboard[j][i]);
tempboard[i][j] = tempboard[j][i];
tempboard[j][i] = temp;
console.log("changed:"+tempboard[j][i]+""+tempboard[i][j]);
}
}
I think it will be easier to build a new array based on the old one.
In the below code a new array is build in reverse based on the original one.
arr = [[11, 12, 13], [21, 22, 23], [31, 32, 33], [41, 42, 43]];
console.log(JSON.stringify(Rotate2D(arr)));
function Rotate2D(array) {
//Create a new empty array with the same size as the original one.
let returnArr = [...Array(array.length)].map(e => Array(array[0].length));
let maxIndexI = array.length - 1;
let maxIndexJ = array[0].length - 1;
//Fill the return array rotated
for (let i = 0; i < array.length; i++) {
for (let j = 0; j < array[0].length; j++) {
returnArr[maxIndexI - i][maxIndexJ - j] = array[i][j]
}
}
return returnArr;
}Try adding "let" keyword to your for loop, it could be an hoisting issue;
for(let i = 0; i < board.length; i++){
for(let j = 0; j < board[0].length; j++){
/*a = tempboard[i][j];
b = tempboard[j][i];
temp = a;
a = b;
b = temp;
console.log(a+" "+b);*/
temp = tempboard[i][j];
console.log("unchanged:"+tempboard[i][j]+""+tempboard[j][i]);
tempboard[i][j] = tempboard[j][i];
tempboard[j][i] = temp;
console.log("changed:"+tempboard[j][i]+""+tempboard[i][j]);
}
}