Char array

A Char array stores characters together. In some VB.NET programs we need to use an array of characters instead of a String.

With Char arrays we employ certain spatial memory optimizations. This type is a useful construct. We can replace StringBuilder usage.

Example

This program declares and instantiates a char array in 3 ways. Usually in programs, the shortest syntax form is best, as it reduces the amount of text to read.

Module Module1
    Sub Main()
        ' Version 1: use the initializer syntax.
        Dim array1() As Char = {"a", "b", "c"}

        ' Version 2: use the long syntax.
        Dim array2(2) As Char
        array2(0) = "a"
        array2(1) = "b"
        array2(2) = "c"

        ' Version 3: another syntax.
        Dim array3() As Char = New Char() {"a", "c", "c"}

        ' Display lengths.
        Console.WriteLine(array1.Length)
        Console.WriteLine(array2.Length)
        Console.WriteLine(array3.Length)
    End Sub
End Module
3
3
3

Example 2

With a char array, we can allocate the Char buffer all at once, and then assign into each element. We do not need to resize the buffer.

Module Module1
    Sub Main()
        ' Allocate array of 100 characters.
        Dim array(100) As Char

        ' Fill array with a character.
        For index As Integer = 0 To 100
            array(index) = "-"
        Next

        ' Write some characters.
        Console.WriteLine(array(0))
        Console.WriteLine(array(100))
    End Sub
End Module
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-

ToCharArray

The easiest way to get a char array is probably ToCharArray. We can specify a string literal, and create an array from the characters with this function in just one line.

Module Module1

    Sub Main()
        Dim value As String = "test"

        ' Get char array from string.
        Dim array() As Char = value.ToCharArray()

        ' Loop and print the chars.
        For Each element As Char In array
            Console.WriteLine("CHAR: {0}", element)
        Next
    End Sub

End Module
CHAR: t
CHAR: e
CHAR: s
CHAR: t

Performance

How much faster is using a Char array to build up a sequence of characters in memory than is using a StringBuilder? This optimization can result in a 10X speedup.

A char array is the ideal array type for building up character data. It conforms to the standard array syntax in VB.NET. It can help many programs.