Why is this happening!

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Ok, so im creating a window that basically inserts the data entered into a SQL database..

But its probably a simple error im making here.. But for some reason when i leave a textbox blank, it still says that it has an incorrent string input.

here is the if statement of which checks it has a null value or not.

C#

if (quantityAvailableTextBox.Text != null)
{ p.QuantityAvailable = Convert.ToInt32(quantityAvailableTextBox.Text); }
else { }

Why is this happen, again, im sure its a simply solution... But for some reason, because of the fact that the textbox.text is null it should skip and go straight to the else... but instead it goes through the if code.

Posted 11-May-14 10:51am

Chris_Burns

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[no name] 11-May-14 16:55pm

You should be using string.IsNullOrWhitespace() instead of just checking for null, which I do not believe that it ever would be.

[no name] 11-May-14 17:01pm

Thank you my friend, I knew it was something simple 😂😂

[no name] 11-May-14 17:11pm

You're welcome. For added safety I would used Int32.TryParse instead of the convert.

[no name] 11-May-14 17:17pm

Thank you:) but how come? What's the benefits of using that? How is it safer? I'm asking in a pupil asking his teach kind of way 😂😂

[no name] 11-May-14 17:19pm

TryParse returns a bool for success/failure. If the conversion fails, it does not throw an exception. Convert throws an exception.

[no name] 11-May-14 17:20pm

Oh and Manas' solution would work also.

[no name] 11-May-14 18:40pm

Thank you my friend :)

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Manas Bhardwaj · Accepted Answer · 2014-05-11T10:55:00

Solution 1

Use IsNullOrEmpty[^]

C#

if (!string.IsNullOrEmpty(quantityAvailableTextBox.Text))
{
    p.QuantityAvailable = Convert.ToInt32(quantityAvailableTextBox.Text);
}
else { }

Posted 11-May-14 10:55am

Manas Bhardwaj

v2

Comments

[no name] 11-May-14 18:46pm

Or IsNullOrWhitespace depending on his version of the framework :-)

Manas Bhardwaj 12-May-14 3:38am

Yeah, old habits die hard. Thanks :)