Two-dimensional. 2D arrays have complex syntax. We have data that should be stored in rows and columns. With a two-dimensional array, we store a rectangular collection of elements.
Step 1 This program populates a new 2D array. The "," syntax is used to declare the array as a two-dimensional array.
Step 2 We call GetUpperBound—this returns how many elements are in a dimension (bound) of the array.
Step 3 We loop over the elements in the 2D array, and write them to the screen with Console.Write.
Module Module1
Sub Main()
' Step 1: declare two-dimensional array of strings.
Dim values(,) As String =
New String(,) {{"AA", "BB"},
{"CC", "DD"}}
' Step 2: get bounds of the array.
Dim bound0 As Integer = values.GetUpperBound(0)
Dim bound1 As Integer = values.GetUpperBound(1)
' Step 3: loop over all elements.
For i As Integer = 0 To bound0
For x As Integer = 0 To bound1
' Get element.
Dim s1 As String = values(i, x)
Console.Write(s1)
Console.Write(" "c)
Next
Console.WriteLine()
Next
End Sub
End ModuleAA BB
CC DD
Three-dimensional. Arrays sometimes have more than one or two dimensions. Three-dimensional arrays are rarely useful. But the syntax is easy to understand.
Detail When you create a 3D array, please specify the dimensions of the array with the maximum indexes of each dimension.
Next To assign elements within the multidimensional array we use three numbers separated by commas.
Tip The argument to GetLength is the dimension index. GetLength returns an element count, not a maximum index of the dimension.
Module Module1
Sub Main()
' Declare 3D array.' ... Specify maximum indexes of dimensions.
Dim threeD(2, 4, 3) As Integer
threeD(0, 0, 0) = 1
threeD(0, 1, 0) = 2
threeD(0, 2, 0) = 3
threeD(0, 3, 0) = 4
threeD(0, 4, 0) = 5
threeD(1, 1, 1) = 2
threeD(2, 2, 2) = 3
threeD(2, 2, 3) = 4
' Loop over three dimensions and display.
For i As Integer = 0 To threeD.GetLength(2) - 1
For y As Integer = 0 To threeD.GetLength(1) - 1
For x As Integer = 0 To threeD.GetLength(0) - 1
Console.Write(threeD(x, y, i))
Next
Console.WriteLine()
Next
Console.WriteLine()
Next
End Sub
End Module100
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500
000
020
000
000
000
000
000
003
000
000
000
000
004
000
000
Jagged array. This kind of array is uneven in shape—it is an array of arrays. If the subarrays you need vary in length, a jagged array becomes extremely efficient.
Info Temporary arrays are created in the standard way in VB.NET and then assigned to elements in the jagged array.
Finally Two nested For-loops are used to loop through the top-level array and all the subarrays.
Module Module1
Sub Main()
' 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 To jagged.Length - 1
' Loop through elements in subarrays.
Dim inner As Integer() = jagged(i)
For a As Integer = 0 To inner.Length - 1
Console.Write(inner(a))
Console.Write(" "c)
Next
Console.WriteLine()
Next
End Sub
End Module1 2 3
0
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A review. Arrays are powerful things. With them we gain the ability to access a unit of data with an integer, not a name. This allows us to create large and complex data sets and use them.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
This page was last updated on Nov 29, 2023 (simplify).
