DataGridView RowCount vs Rows.Count

Question

Hello,

RowCount: Gets or sets the number of rows displayed in the DataGridView

Rows.Count: Returns the number of rows

What does it mean, when they can have different values?

The only condition I can imagine is if a row is invisible, then RowCount does not count it, anything else that can cause different values?

Thanks.

• I need to check if all rows are selected, so don't know which one is a better way to go?

DataGridView.SelectedRows.Count = DataGridView.Rows.Count
vs
DataGridView.SelectedRows.Count = DataGridView.RowCount

Answer 1

I constructed this to find out what happens if RowCount is changed. See remarks here.

Private Sub Form1_Shown(sender As Object, e As EventArgs) Handles Me.Shown

    'sample data

    DataGridView1.ColumnCount = 4

    DataGridView1.ColumnHeadersVisible = True

    ' Set the column header style.

    Dim columnHeaderStyle As New DataGridViewCellStyle()

    columnHeaderStyle.BackColor = Color.Beige

    columnHeaderStyle.Font = New Font("Verdana", 10, FontStyle.Bold)

    DataGridView1.ColumnHeadersDefaultCellStyle = columnHeaderStyle

    ' Set the column header names.

    DataGridView1.Columns(0).Name = "Recipe"

    DataGridView1.Columns(1).Name = "Category"

    DataGridView1.Columns(2).Name = "Main Ingredients"

    DataGridView1.Columns(3).Name = "Rating"

    ' Populate the rows.

    Dim row1() As String = {"Meatloaf", "Main Dish", "ground beef", "**"}

    Dim row2() As String = {"Key Lime Pie", "Dessert", "lime juice, evaporated milk", "****"}

    Dim row3() As String = {"Orange-Salsa Pork Chops", "Main Dish", "pork chops, salsa, orange juice", "****"}

    Dim row4() As String = {"Black Bean and Rice Salad", "Salad", "black beans, brown rice", "****"}

    Dim row5() As String = {"Chocolate Cheesecake", "Dessert", "cream cheese", "***"}

    Dim row6() As String = {"Black Bean Dip", "Appetizer", "black beans, sour cream", "***"}

    Dim rows() As Object = {row1, row2, row3, row4, row5, row6}

    Dim rowArray As String()

    For Each rowArray In rows

        DataGridView1.Rows.Add(rowArray)

    Next rowArray

End Sub

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

    Debug.WriteLine(DataGridView1.Rows.Count)

    DataGridView1.RowCount = DataGridView1.Rows.Count - 2

    Debug.WriteLine(DataGridView1.Rows.Count)

End Sub

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click

    Debug.WriteLine(DataGridView1.Rows.Count)

    DataGridView1.RowCount = DataGridView1.Rows.Count + 3

    Debug.WriteLine(DataGridView1.Rows.Count)

End Sub

Answer 2

The content of the question has changed. If there are hidden rows, if all rows are selected it should look like this:

Public Shared Function IsFullRowSelected(view As DataGridView) As Boolean
    For Each row As DataGridViewRow In view.Rows
        If row.Visible AndAlso Not row.Selected Then
            Return False
        End If
    Next
    Return True
End Function

Answer 3

The best approach to working with a DataGridView is to have a DataSource such as a DataTable or a List that is set to the DataSource of a BindingSource which then becomes the DataSource to the DataGridView. Doing this assist in other things besides what you are after, mainly going this way means you can work with data in 99 percent of the time by asking a question e.g. if the data source is a DataTable to get at the current row case Current property of the current row to a DataRowView then to a DataRow.

For your question, I have a DataGridView named ProductsDataGridView and a BindingSource named _mainBindingSource. To see if all rows are selected use.

if (ProductsDataGridView.SelectedRows.Count == _mainBindingSource.Count)
{
    // do something
}

Or

If ProductsDataGridView.SelectedRows.Count = _mainBindingSource.Count Then
	' do something
End If