Initializing Arrays

You can use array elements wherever you'd use a similarly typed variable that wasn't part of an array.

Here's how we'd store values in the arrays we've been working with:

k[0] = 2; k[1] = 5; k[2] = -2; yt[6] = 7.5f; names[4] Fred; This step is called initializing the array or, more precisely, initializing the elements of the array. Sometimes the phrase "initializing the arraywould be reserved for when we initialize all the elements of the array.

For even medium sized arrays, it's unwieldy to specify each element individually. It is often helpful to use for loops to initialize the array. For instance here is a loop that fills an array with the squares of the numbers from 0 to 100.

float[] squares = new float[101]; for (int i=0; i <= 100; i++) { squares[i] = i*i; } Two things you should note about this code fragment:

• Watch the fenceposts! Since array subscripts begin at zero we need 101 elements if we want to include the square of 100.
• Although i is an int it becomes a float when it is stored in squares, since we've declared squares to be an array of floats.

float[] squares = new float[101]; for (int i=0, i < squares.length; i++) { squares[i] = i*i; } Note that the <= changed to a < to make this work.

Shortcuts

We can declare and allocate an array at the same time like this:

int[] k = new int[3]; float[] yt = new float[7]; String[] names = new String[50]; We can even declare, allocate, and initialize an array at the same time providing a list of the initial values inside brackets like so:

int[] k = {1, 2, 3}; float[] yt = {0.0f, 1.2f, 3.4f, -9.87f, 65.4f, 0.0f, 567.9f};