Simple way to check if a string is a correct integer?

[Henke]

Hi!

Is there a simple way to check if a string entered in a text box is a valid
integer?

Thanks in advance!
/Henke

[Paul Henon]

Use a regular expression to match the input with a pattern, say:

Match m=Regex.Match(i nputString,"^[0-9]{1,}$";
if (m.Success) {
//whatever you want to do
}

The pattern above basically says:
[0-9] : check for the occurance of digits 0 to 9
{1,} : these can occur from 1 to infinite times
^ : there must be nothing in front of these digits
$ : there must be nothing behind these digits

success,
Paul

Is there a simple way to check if a string entered in a text box is a valid integer?

[Jon Skeet]

Henke <he********@hot mail.com> wrote:

Is there a simple way to check if a string entered in a text box is a valid
integer?

The easiest thing to do is just parse it:

Convert.ToInt32 (myString);

and catch the exception that you get if it's not valid.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet/
If replying to the group, please do not mail me too

[Peter Rilling]

Alternatively you could reference the VB.NET assembly located in the
references dialog and use the IsNumeric function available in VB.NET.

"Jon Skeet" <sk***@pobox.co m> wrote in message
news:MP******** *************** *@news.microsof t.com...

Henke <he********@hot mail.com> wrote:

Is there a simple way to check if a string entered in a text box is a valid integer?

The easiest thing to do is just parse it:

Convert.ToInt32 (myString);

and catch the exception that you get if it's not valid.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet/
If replying to the group, please do not mail me too

[Henke]

Thnaks for your answer, but on what object should I use IsNumeric? Is it a
static function on some VB data type?

/Henke

"Peter Rilling" <pe***@nospam.r illing.net> skrev i meddelandet
news:%2******** **********@TK2M SFTNGP09.phx.gb l...

Alternatively you could reference the VB.NET assembly located in the
references dialog and use the IsNumeric function available in VB.NET.

"Jon Skeet" <sk***@pobox.co m> wrote in message
news:MP******** *************** *@news.microsof t.com...

Henke <he********@hot mail.com> wrote:

Is there a simple way to check if a string entered in a text box is a valid integer?

The easiest thing to do is just parse it:

Convert.ToInt32 (myString);

and catch the exception that you get if it's not valid.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet/
If replying to the group, please do not mail me too

[Jon Skeet]

Henke <he********@hot mail.com> wrote:

Thnaks for your answer, but on what object should I use IsNumeric? Is it a
static function on some VB data type?

You'd call Microsoft.Visua lBasic.Informat ion.IsNumeric(s tring)

You'd also need to add a reference to the Microsoft.Visua lBasic.dll
assembly.

Personally I'd steer clear of using the VB stuff - it makes your code
less portable (eg to Mono) and just feels a bit icky to me.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet/
If replying to the group, please do not mail me too

[Henke]

Ok, thanks. I think I use the Regex-way...
/Henke

"Jon Skeet" <sk***@pobox.co m> skrev i meddelandet
news:MP******** *************** *@news.microsof t.com...

Henke <he********@hot mail.com> wrote:

Thnaks for your answer, but on what object should I use IsNumeric? Is it a static function on some VB data type?

You'd call Microsoft.Visua lBasic.Informat ion.IsNumeric(s tring)

You'd also need to add a reference to the Microsoft.Visua lBasic.dll
assembly.

Personally I'd steer clear of using the VB stuff - it makes your code
less portable (eg to Mono) and just feels a bit icky to me.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet/
If replying to the group, please do not mail me too

[ncaHammer]

"Henke" <he********@hot mail.com> wrote in message
news:Oq******** ********@TK2MSF TNGP09.phx.gbl. ..

Is there a simple way to check if a string entered in a text box is a valid integer?

http://aspalliance.com/Ambrose/Articles/IsNumeric.aspx
seems that Double.TryParse (and then check if is in int.MinValue - MaxValue
range) is the fastest

try to avoid exceptions for normal app flow

[Stephen Alpert]

On Wed, 6 Aug 2003 08:36:05 +0200, "Henke" <he********@hot mail.com> wrote:

Hi!

Is there a simple way to check if a string entered in a text box is a valid
integer?

I just refused to accept anything but digits and backspace!

//
// OnKeyPress - only accept digits..
//
private void OnKeyPress(obje ct sender,
System.Windows. Forms.KeyPressE ventArgs e)
{
e.Handled = !(Char.IsDigit( e.KeyChar) || e.KeyChar == 8); // bksp
}
my email Fg**********@vq k.pbz is encrypted with ROT13 (www.rot13.org)

[Thomas Gagné]

isNumeric sounds like it would have been a great method to be inside of
String. Can it be added?

Jon Skeet wrote:

Henke <he********@hot mail.com> wrote:

Thnaks for your answer, but on what object should I use IsNumeric? Is it a
static function on some VB data type?

You'd call Microsoft.Visua lBasic.Informat ion.IsNumeric(s tring)

You'd also need to add a reference to the Microsoft.Visua lBasic.dll
assembly.

Personally I'd steer clear of using the VB stuff - it makes your code
less portable (eg to Mono) and just feels a bit icky to me.

--
..tom
remove email address' dashes for replies
opensource middleware at <http://isectd.sourcefo rge.net>
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