I think you are looking for the correct validation of a column of a text field in a datagrid format? if so you could take a look at this link
http://www.codeproject.com/Questions/93691/Validations-inside-DataGridView-TextboxColumn.aspx
EDIT 1:
You can use this solution, but it only checks numbers or if you want to check the text, you can change the code.
private void dataGridView1_CellValidating(object sender, DataGridViewCellValidatingEventArgs e)
{
DataGridViewTextBoxCell cell = dataGridView1[2, e.RowIndex] as DataGridViewTextBoxCell;
if (cell != null)
{
if (e.ColumnIndex == 2)
{
char[] chars = e.FormattedValue.ToString().ToCharArray();
foreach (char c in chars)
{
if (char.IsDigit(c) == false)
{
MessageBox.Show("You have to enter digits only");
e.Cancel = true;
break;
}
}
}
}
}
NOTE: this code is not verified.
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