.Net Code For RtlMoveMemory API function to copy part of a two-dimensional array

[nandagopal]

Enter the rows and columns that you want to copy out of the two-dimensional array. When you click the Copy button, the following code executes. The code copies the values shown in the form's TextBoxes into a two-dimensional array and highlights the entries you selected.

Next the program loops through the rows you selected, using RtlMoveMemory to copy the choosen parts of the two-dimensional array.

Note that this is different from the way the Visual Basic 6 version works because Visual Basic 6 stores two-dimensional arrays in column-major order (it places the items in a column in adjacent memory locations) while Visual Basic .NET stores them in row-major order (it places the items in a row in adjacent memory locations).

Code Select Expand

Private Sub btnCopy_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles btnCopy.Click
    ' Reset all text box colors.
    For Each ctl As Control In Me.Controls
        If TypeOf ctl Is TextBox Then
            ctl.ForeColor = Color.Black
            ctl.BackColor = Color.White
        End If
    Next ctl

    ' Make the two-dimensional array (0 To 3, 0 To 4).
    Dim in_array(3, 4) As Integer
    For r As Integer = 0 To 3
        For c As Integer = 0 To 4
            Dim control_name As String = "TextBox" & (r * 5 _
                + c + 1).ToString()
            Dim txt As TextBox = FindControl(control_name)
            in_array(r, c) = Integer.Parse(txt.Text)
        Next c
    Next r

    ' Color the selected entries.
    Dim row_min As Integer = Integer.Parse(txtRowMin.Text) _
        - 1
    Dim row_max As Integer = Integer.Parse(txtRowMax.Text) _
        - 1
    Dim col_min As Integer = Integer.Parse(txtColMin.Text) _
        - 1
    Dim col_max As Integer = Integer.Parse(txtColMax.Text) _
        - 1
    For r As Integer = row_min To row_max
        For c As Integer = col_min To col_max
            Dim control_num As Integer = r * 5 + c + 1
            Dim field As TextBox = FindControl("TextBox" & _
                control_num.ToString())
            field.BackColor = Color.Black
            field.ForeColor = Color.White
        Next c
    Next r

    ' Copy the data into out_array using MemCopy.
    Dim num_rows As Integer = row_max - row_min + 1
    Dim num_cols As Integer = col_max - col_min + 1
    Dim bytes_per_row As Integer = Len(col_min) * (num_cols)
    Dim out_array(bytes_per_row * num_rows - 1) As Integer
    Dim idx As Integer = 0
    For r As Integer = row_min To row_max
        MoveMemory(out_array(idx), in_array(r, col_min), _
            bytes_per_row)
        idx += num_cols
    Next r

    ' Print the output values.
    Dim result As String = ""
    For i As Integer = 0 To num_rows * num_cols - 1
        result &= out_array(i).ToString("0") & " "
    Next i
    txtResult.Text = result
End Sub