Question

I am using winforms and C#,.

When i try to get datagridviewcheckbox state, if the checkbox not true it shows “Null Reference Exception was caught” as Exception.

My Code is

foreach (DataGridViewRow fees_row in this.dataGridView2.Rows)
{
    if ((bool) fees_row.Cells[0].Value == true)
    {
    }
}

The error is in the line:

if ((bool) fees_row.Cells[0].Value == true)

how to set datagridview checkbox value not null. or escape this exception.

Answer 1

You need to make sure that the DataGridViewCell object is not null first, before trying to interrogate its value. That’s what’s causing the NullReferenceException—you’re interrogating the Value property of a null object!

Change your code to look like this:

foreach (DataGridViewRow fees_row in this.dataGridView2.Rows)
{
    var cell = fees_row.Cells[0];
    if (cell != null)
    {
        var value = cell.Value;
        if (value != null && (bool)value == true)
        {
            // Do whatever...
        }
    }
}

But before someone else leaves a snarky comment, there’s generally no reason to check a Boolean value against a literal true. All you have to write is if (boolValue)