C# in a Nutshell, Second Edition

Arrays

type [*]
+ array-name = 
[
  new type [ dimension+ ][*]*; |
  { value1, value2, ... };
]

Note that [*] is the set: [ ] [,] [,,] ...

Arrays allow a group of elements of a particular type to be stored in a contiguous block of memory. An array is specified by placing square brackets after the element type. For example:

char[ ] vowels = new char[ ] {'a','e','i','o','u'};
Console.WriteLine(vowels [1]); // Prints "e"

This prints “e” because array indexes start at 0. To support other languages, .NET can create arrays based on arbitrary start indexes, but all the libraries use zero-based indexing. Once an array has been created, its length cannot be changed. However, the System.Collection classes provide dynamically sized arrays, as well as other data structures, such as associative (key/value) arrays.

Multidimensional Arrays

Multidimensional arrays come in two varieties: rectangular and jagged. Rectangular arrays represent an n-dimensional block, while jagged arrays are arrays of arrays. In this example we make use of the for loop, which is explained in the statements section. The for loops here simply iterate through each item in the arrays.

// rectangular
int [,,] matrixR = new int [3, 4, 5]; // creates 1 big cube
// jagged
int [ ][ ][ ] matrixJ = new int [3][ ][ ];
for (int i = 0; i < 3; i++) {
   matrixJ[i] = new int [4][ ];
   for (int j = 0; j < 4; j++)
      matrixJ[i][j] = new int [5];
} 
// assign an element
matrixR [1,1,1] = matrixJ [1][1][1] = 7;

Local Field Array Declarations

For convenience, ...