N-Dimensional Arrays

n-dimensional, or multidimensional, arrays are easy to declare and use. They work just like single-dimensional arrays, except that a comma is placed within the square brackets between the array dimensions.

It’s easy to see why you might want to use a two-dimension array to represent the “board” of a game like checkers or chess. N-dimensional arrays become useful when more information is needed to adequately model a situation. For example, a three dimensional array might be used to store stock prices and volume over time.

Here are the declarations for a two-dimensional integer array and a three-dimensional string array:

Let’s have a look at an example. First, declare and instantiate a two-dimensional integer array the2d, with five “rows” and three “columns”:

Next, populate the array by assigning as a value to each element its row times its column:

for (int i = 0; i < rows; i++) {
for (int j = 0; j < cols; j++){
the2d[i,j] = i * j;
}
}

Next, iterate through both dimensions of the array. For each element, create a string consisting of its coordinates in the array followed by its value, and add it to a ListBox:

for (int i = 0; i < rows; i++) {
for (int j = 0; j < cols; j++){
string theItem = "the2d [" + i.ToString() + "," + j.ToString() +
"] is "
+ the2d[i,j].ToString() + ".";
lstMulti.Items.Add(theItem);
}
}

If you run the code in the listing, you’ll see that the contents of the array is displayed in the ListBox.

Listing: Creating and Displaying a Two-Dimensional Array

private void btnMulti_Click(object sender, System.EventArgs e) {
const int rows = 5;
const int cols = 3;


// declare 5X3 array
int [,] the2d = new int [rows, cols];


// populate the array
for (int i = 0; i < rows; i++) {
for (int j = 0; j < cols; j++) {
the2d[i,j] = i*j;
}
}


// display it
for (int i = 0; i < rows; i++) {
for (int j = 0; j < cols; j++) {
string theItem = "the2d [" + i.ToString() + "," + j.ToString()
+ "] is " + the2d[i,j].ToString() + ".";
lstMulti.Items.Add(theItem);
}
}
}

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