Question

How to merge two 2D arrays vertically in VB.NET

Answer 1

Imports System

Module Program

    Sub Main()
        Dim a(,) As Integer = {
            {1, 2},
            {3, 4}
        }

        Dim b(,) As Integer = {
            {5, 6},
            {7, 8}
        }

        Dim rows As Integer = a.GetLength(0) + b.GetLength(0)
        Dim cols As Integer = a.GetLength(1)

        Dim merged(rows - 1, cols - 1) As Integer

        Dim index As Integer = 0

        For i As Integer = 0 To a.GetLength(0) - 1
            CopyRow(a, i, merged, index)
            index += 1
            CopyRow(b, i, merged, index)
            index += 1
        Next

        PrintMatrix(merged)
    End Sub

    Sub CopyRow(src(,) As Integer, srcRow As Integer, dst(,) As Integer, dstRow As Integer)
        For j As Integer = 0 To src.GetLength(1) - 1
            dst(dstRow, j) = src(srcRow, j)
        Next
    End Sub

    Sub PrintMatrix(arr(,) As Integer)
        For i As Integer = 0 To arr.GetLength(0) - 1
            For j As Integer = 0 To arr.GetLength(1) - 1
                Console.Write(arr(i, j) & " ")
            Next
            Console.WriteLine()
        Next
    End Sub

End Module



' run:
'
' 1 2 
' 5 6 
' 3 4 
' 7 8
'

 

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Answer 2

Imports System

Module Program

    Sub Main()
        Dim a(,) As Integer = {
            {1, 2},
            {3, 4}
        }

        Dim b(,) As Integer = {
            {5, 6},
            {7, 8}
        }

        Dim rows As Integer = a.GetLength(0) + b.GetLength(0)
        Dim cols As Integer = a.GetLength(1)

        Dim merged(rows - 1, cols - 1) As Integer

        ' Copy A
        For i As Integer = 0 To a.GetLength(0) - 1
            For j As Integer = 0 To cols - 1
                merged(i, j) = a(i, j)
            Next
        Next

        ' Copy B
        For i As Integer = 0 To b.GetLength(0) - 1
            For j As Integer = 0 To cols - 1
                merged(i + a.GetLength(0), j) = b(i, j)
            Next
        Next

        PrintMatrix(merged)
    End Sub

    Sub PrintMatrix(arr(,) As Integer)
        For i As Integer = 0 To arr.GetLength(0) - 1
            For j As Integer = 0 To arr.GetLength(1) - 1
                Console.Write(arr(i, j) & " ")
            Next
            Console.WriteLine()
        Next
    End Sub

End Module



' run:
'
' 1 2 
' 3 4 
' 5 6 
' 7 8
'

 

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