Map a 2D array onto a 1D array

Question

I want to represent a 2D array with a 1D array. A function will pass the two indicies (x,y) and the value to store. These two indicies would represent a single element of a 1D array, and set it accordingly. I know the 1D array needs to have the size of arrayWidth × arrayHeight, but I don't know how to set each element.

For example, how do I distinguish (2,4,3) from (4,2,3)? I tried setting the array as the x*y, but 2*4 and 4*2 would result in the same spot in the array and I need them to be different.

Answer 1

You need to decide whether the array elements will be stored in row order or column order and then be consistent about it. http://en.wikipedia.org/wiki/Row-major_order

The C language uses row order for Multidimensional arrays

To simulate this with a single dimensional array, you multiply the row index by the width, and add the column index thus:

 int array[width * height];

 int SetElement(int row, int col, int value)
 {
    array[width * row + col] = value;  
 }