in the event of DataGridView
CellValidating
or RowValidating
private void dataGridView1_CellValidating(object sender, DataGridViewCellValidatingEventArgs e)
{
if (dataGridView1.IsCurrentCellDirty)
if (e.ColumnIndex == 0)
{
if (string.IsNullOrWhiteSpace(dataGridView1[e.ColumnIndex, e.RowIndex].EditedFormattedValue.ToString()))
{
e.Cancel = true;
MessageBox.Show("Please enter some text before you leave.");
}
else
{
//Some logic here
}
}
}