Checking For Invalid Characters

[Darin Browne]

Is there anything built into .NET Framework I could use
to check if a string only has numerics and alphanumerics
in it? If anything else but a numeric or alpha has been
entered I want it to error.

Thanks.

[Nicholas Paldino [.NET/C# MVP]]

Darin,

You can cycle through all of the characters in the string, and then
check to see if the character is valid. You can do something like this:

// Assuming pchrChar is the character.
bool pblnAlphaNumeric = ('A' <= pchrChar && pchrChar <= 'Z') || ('a' <=
pchrChar && pchrChar <= 'z') || ('0' <= pchrChar && pchrChar <= '9');

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"Darin Browne" <an*******@discussions.microsoft.com> wrote in message
news:0a****************************@phx.gbl...

Is there anything built into .NET Framework I could use
to check if a string only has numerics and alphanumerics
in it? If anything else but a numeric or alpha has been
entered I want it to error.

Thanks.

[Bobby C. Jones]

You can use the Parse method of the numeric types.

float realNumData = 0;
try
{
realNumData = float.Parse(<textToParse>);
}
//The string could not be parsed into a number
catch (FormatException)
{
this.statusBar1.Text = "Invalid real number";
}
//The number is out of range of the float type
catch (OverflowException)
{
this.statusBar1.Text = "Number out of range";
}
--
Bobby C. Jones
www.AcadX.com

"Darin Browne" <an*******@discussions.microsoft.com> wrote in message
news:0a****************************@phx.gbl...

Is there anything built into .NET Framework I could use
to check if a string only has numerics and alphanumerics
in it? If anything else but a numeric or alpha has been
entered I want it to error.

Thanks.

[Ignacio Machin \( .NET/ C# MVP \)]

Hi,

You could also use a regex, like:
Regex.IsMatch( theString, "^[\w|\d]*$");

Please, the above regular expression was not tested , test it if you are
going to use it !!

Cheers,

--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation

"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard.caspershouse.com> wrote in
message news:%2****************@TK2MSFTNGP09.phx.gbl...

Darin,

You can cycle through all of the characters in the string, and then
check to see if the character is valid. You can do something like this:

// Assuming pchrChar is the character.
bool pblnAlphaNumeric = ('A' <= pchrChar && pchrChar <= 'Z') || ('a' <=
pchrChar && pchrChar <= 'z') || ('0' <= pchrChar && pchrChar <= '9');

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"Darin Browne" <an*******@discussions.microsoft.com> wrote in message
news:0a****************************@phx.gbl...

Is there anything built into .NET Framework I could use
to check if a string only has numerics and alphanumerics
in it? If anything else but a numeric or alpha has been
entered I want it to error.

Thanks.

[Mattias Sjögren]

// Assuming pchrChar is the character.
bool pblnAlphaNumeric = ('A' <= pchrChar && pchrChar <= 'Z') || ('a' <=
pchrChar && pchrChar <= 'z') || ('0' <= pchrChar && pchrChar <= '9');

That's pretty i18n unfriendly code. I'd use Char.IsLetterOrDigit()
instead.

Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
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