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Check If A String Value Is Numeric

, 6 Mar 2006 CPOL
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A way to determine if a string value has a specific Style Number And/OR Culture

Introduction

This article will give you a way to determine if a given string has a valid number style (Integer, Float, Currency, etc.) according to specified/current culture.

Background

In all VBScript and Visual Basic applications, there is a built-in function called IsNumeric / IsCurrency, but in C# there is no built-in function with the same functionality.
I have investigated a little and found out that all given solutions always use try catch to find out if the given string value can be parsed.

That seemed like a good way to test it, BUT what if the number contains commas or a currency sign?
Then I have to add another check to this code and strip down the non numeric sign and test the result.
Here I present a simple way that is supported by C#.

The Solution

In the code shown below, I actually use a built-in functionality of C# to determine if a given string value stands up to the requirements I want.

public bool isNumeric(string val, System.Globalization.NumberStyles NumberStyle)
{
    Double result;
    return Double.TryParse(val,NumberStyle,
		System.Globalization.CultureInfo.CurrentCulture,out result);
}

The above function allow me to test if the given string stands up to one or more of the following styles:

  • Hex Number
  • Number
  • Currency
  • Float

A more detailed list and explanation regarding System.Globalization.NumberStyles can be found here.

Examples

If you want to test for an integer number, then do the following:

isNumeric("42000", System.Globalization.NumberStyles.Integer)

If you want to test for an integer number separated with commas, then do the following:

isNumeric("42,000", System.Globalization.NumberStyles.Integer | 
	System.Globalization.NumberStyles.AllowThousands)

Using Other Cultures

I use the current culture as shown in the code below.
A list of all available culture names can be obtained here.

public bool isNumeric
    (string val, System.Globalization.NumberStyles NumberStyle, string CultureName)
{
    Double result;
    return Double.TryParse(val,NumberStyle,new System.Globalization.CultureInfo
				(CultureName),out result);
}

There are many ways to approach this problem, I chose the one that suits beginner levels and does not involve any Regular Expression which requires a higher level of expertise.

If you are interested in a solution that involves Regular Expressions, please take a look at the following links:

Enjoy and tell me your findings.

History

  • 7th March, 2006: Initial post

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Leon Kovach
Web Developer
Israel Israel
No Biography provided

Comments and Discussions

 
GeneralMy vote of 5 PinprofessionalCanny Brisk1-Sep-13 20:45 
QuestionSimple VBScript program to Validate Numeric value PinmemberGauthamvit200310-Jul-11 7:46 
AnswerRe: Simple VBScript program to Validate Numeric value PinprofessionalCanny Brisk1-Sep-13 20:46 
GeneralRegEx for this function [modified] PinmemberAnthony Urwin8-Sep-10 0:24 
GeneralRe: RegEx for this function [modified] PinmemberMember 416585117-Apr-14 3:24 
QuestionDecimals? Pinmembersmcirish13-Jan-10 3:06 
AnswerRe: Decimals? PinprofessionalCanny Brisk1-Sep-13 20:47 
GeneralYes yes yes PinmemberL C D8-Dec-08 15:04 
GeneralRe: Yes yes yes PinmemberDush Abe26-Jun-13 12:03 
GeneralAnother way A one-liner too :) PinmemberHusko25-Mar-08 10:00 
Questionhow to check if string is int and return boolean Pinmembermax_dev2006@yahoo.com11-Oct-06 22:58 
AnswerRe: how to check if string is int and return boolean PinmemberGhecco17-Oct-06 5:31 
GeneralRe: how to check if string is int and return boolean Pinmembertfaiz20-Jun-11 22:29 
GeneralWorking for me PinmemberThisTrain7-Mar-06 5:29 
GeneralGood Thinking PinmemberThisTrain7-Mar-06 5:17 
GeneralNo, no, no Pinmembernorm.net7-Mar-06 4:35 
GeneralRe: No, no, no PinmemberMarc Brooks7-Mar-06 4:41 
GeneralRe: No, no, no Pinmembernorm.net7-Mar-06 8:49 
GeneralRe: No, no, no Pinmembernorm.net7-Mar-06 8:49 
GeneralRe: No, no, no Pinmemberkingbin7-Mar-06 5:54 
GeneralRe: No, no, no Pinmembernorm.net7-Mar-06 8:49 
GeneralRe: No, no, no Pinmembercerberiukas14-Mar-06 4:25 
AnswerRe: No, no, no PinmemberLeon Kovach18-Mar-06 22:57 
GeneralRe: No, no, no Pinmemberdave78638313-Aug-07 7:30 

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