Thursday, 12 October 2017

Arrays and Jagged Array


Arrays

An array stores a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type. All arrays consist of contiguous memory locations. The lowest address corresponds to the first element and the highest address to the last element.

Creating Arrays in VB.Net

1.Module Module1
    Sub Main()
             ' Create an array.
             Dim array(2) As Integer
             array(0) = 100
             array(1) = 10
             array(2) = 1
             For Each element As Integer In array
                 Console.WriteLine(element)
             Next
    End Sub
End Module
Output
100
10
1
2.Integer array 2
Module Module1
    Sub Main()
             ' Create array of three integers.
             Dim array() As Integer = {10, 30, 50}
             For Each element As Integer In array
                 Console.WriteLine(element)
             Next
    End Sub
End Module
Output
10
30
50
String array
Module Module1
    Sub Main()
             ' Create array of maximum index 3.
             Dim array(3) As String
             array(0) = "dot"
             array(1) = "net"
             array(2) = "perls"
             array(3) = CStr(2010)
             ' Display.
             For Each element As String In array
                 Console.WriteLine(element)
             Next
    End Sub
End Module
Output
dot
net
perls
2010
Array argument
Module Module1
    Sub Main()
             Dim array() As Integer = {5, 10, 20}
             ' Pass array as argument.
             Console.WriteLine(Example(array))
    End Sub
    ''' <summary>
    ''' Receive array parameter.
    ''' </summary>
    Function Example (ByVal array() As Integer) As Integer
             Return array(0) + 10
    End Function
End Module
Output
15

Jagged Array
A jagged array is uneven in shape. It is an array of arrays. For example, it one array element should be four elements long. Another should be 400 elements long. In this situation a jagged array is extremely efficient.
Eg:-' Create jagged array with maximum index of 2.
Dim jagged()() As Integer = New Integer(2)() {}
' Create temporary array and place in index 0.
Dim temp(2) As Integer
temp(0) = 1
temp(1) = 2
temp(2) = 3
jagged(0) = temp
' Create small temporary array and place in index 1.
Dim temp2(0) As Integer
jagged(1) = temp2
' Use array constructor and place result in index 2.
jagged(2) = New Integer() {3, 4, 5, 6}
' Loop through top-level arrays.
For i As Integer = 0 Tojagged.Length - 1
' Loop through elements in subarrays.
    Dim inner As Integer() = jagged(i)
    For a As Integer = 0 Toinner.Length - 1
Console.Write(inner(a))
Console.Write(" "c)
    Next
Console.WriteLine()
Next
    End Sub
End Module
Output
1 2 3
0
3 4 5 6

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