12.1. One-dimensional arrays

The syntax for array declaration is the same in C# as in Java, except for one difference – when declaring an array, Java permits putting the square brackets either in front of or behind the array's type. C# only allows the former – Putting the square brackets after an array identifier will cause a compilation error. ^[3]

^[3] C/C++ mandates that the square brackets be behind the array type (as in int array[];).

Both the following declarations are okay in Java:

• int MyArray[];

• int []MyArray;

However, only int []MyArray; is legal in C#.

Other than that, the syntax for array declaration, instantiation, and initialization are identical in C# and Java as far as 1D arrays are concerned. Examples are shown below as a refresher and for reference.

• Declaring a 1D array (without instantiating it):

  int []MyArray1;
  object[] MyArray2;
  

  It doesn't matter if the space is between the type and the square brackets, or between the square brackets and the array identifier.

• Declaring and instantiating a 1D array in a single statement:

  int []MyArray1 = new int[3];
  object[] MyArray2 = new object[2];
  

  The statements declare and instantiate MyArray1 as an int array with a size of 3, and MyArray2 as an object array of size 2.

• Declaring, instantiating and initializing a 1D array in a single statement:

  int[] MyArray1 = {1,2,3};
  object[] MyArray2 = {"apple",9};
  

• Accessing a value in a 1D array:

  int Temp = MyArray1[1];
  MyArray1[2] = 99;
  

Beyond 1D arrays, C# supports two types of multi-dimensional arrays – rectangular arrays and jagged arrays. Because Java's multi-dimensional arrays do not map directly into either category, I have chosen to compare Java's implementation with the simpler rectangular arrays.