#1,012 – Options for Array Declaration, Instantiation and Initialization

Recall that there are three steps for using arrays:

  • Declare the array (declare a variable whose type is an array)
  • Instantiate the array (allocate memory for the array)
  • Initialize the array (store values in the array)

Below are examples of the different ways that you can declare, instantiate, and initialize an array.

            // Option 1: Declare, instantiate and initialize in three
            //   steps
            int[] a1;
            a1 = new int[3];
            a1[0] = 1; a1[1] = 2; a1[2] = 3;

            // Option 2: Declare in 1 step, instantiate/initialize in
            //   2nd step
            int[] a2;
            a2 = new int[] {1, 2, 3};

            // Option 3: Declare and instantiate in 1 step,
            //   initialize later.
            int[] a3 = new int[3];  // Must provide size
            a3[0] = 1; a3[1] = 2; a3[2] = 3;

            // Option 4: Declare, instantiate and initialize
            //   in single line. (Using array initializer)
            int[] a4 = new int[] { 1, 2, 3 };

            // Variation: Can omit type
            int[] a5 = new[] { 1, 2, 3 };

            // Variation: Can omit new keyword, inferring type
            int[] a6 = { 1, 2, 3 };
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About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

2 Responses to #1,012 – Options for Array Declaration, Instantiation and Initialization

  1. Thorsten says:

    You can use this too:
    int[] arr = new[] { 1, 2, 3 };

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