I've just tested this code to a messagebox and it works
VB Code:
  1. Dim sb As New StringBuilder()
  2.         Dim row As DataGridViewRow = Me.DataGridView1.Rows(0) 'Reads from the first row
  3.         For Each column As DataGridViewColumn In DataGridView1.Columns
  4.             sb.Append(row.Cells(column.Index).Value.ToString)
  5.             sb.Append(ControlChars.NewLine)
  6.         Next
  7.         RichTextBox1.Text = sb.Tostring
So i'm guessing it will work with a richtextbox. If you need to read from everyrow in your dgv then you'll need to replace the line
VB Code:
  1. Dim row as DatagridviewRow = datagridview1.rows(0)
with the code
VB Code:
  1. For each row as Datagridviewrow in datagridview1.rows
  2. next
and place it around the for loop for the columns.
Hope this helps.

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