C# Array Initialization
Description
An array initialization expression specifies each element of an array.
Syntax
For example:
char[] vowels = new char[] {'a','e','i','o','u'};
or simply:
char[] vowels = {'a','e','i','o','u'};Default Element Initialization
Creating an array always preinitializes the elements with default values.
The default value for a type is the result of a bitwise zeroing of memory.
For example, int is a value type, this allocates 1,000 integers.
The default value for each element will be 0:
int[] a = new int[1000];
Console.Write (a[123]); // 0
Simplified Array Initialization Expressions
There are two ways to shorten array initialization expressions. The first is to omit the new operator and type qualifications:
char[] vowels = {'a','e','i','o','u'};
/*from w w w. jav a2s . co m*/
int[,] rectangularMatrix =
{
{0,1,2},
{3,4,5},
{6,7,8}
};
int[][] jaggedMatrix =
{
new int[] {0,1,2},
new int[] {3,4,5},
new int[] {6,7,8}
};
The second approach is to use the var keyword, which tells the compiler to implicitly type a local variable:
var i = 3; // i is implicitly of type int
var s = "java2s.com"; // s is implicitly of type string
//w w w.ja va 2s . c o m
// Therefore:
var rectMatrix = new int[,] // rectMatrix is implicitly of type int[,]
{
{0,1,2},
{3,4,5},
{6,7,8}
};
var jaggedMat = new int[][] // jaggedMat is implicitly of type int[][]
{
new int[] {0,1,2},
new int[] {3,4,5},
new int[] {6,7,8}
};
You can omit the type qualifier after the new keyword and have the compiler infer the array type with single-dimensional arrays:
var vowels = new[] {'a','e','i','o','u'}; // Compiler infers char[]
The elements must all be implicitly convertible to a single type in order for implicit array typing to work. For example:
var x = new[] {1,10000000000}; // all convertible to long