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Check If A String Value Is Numeric

, 7 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 Pin
Canny Brisk1-Sep-13 21:45
professionalCanny Brisk1-Sep-13 21:45 
QuestionSimple VBScript program to Validate Numeric value Pin
Gauthamvit200310-Jul-11 8:46
memberGauthamvit200310-Jul-11 8:46 
AnswerRe: Simple VBScript program to Validate Numeric value Pin
Canny Brisk1-Sep-13 21:46
professionalCanny Brisk1-Sep-13 21:46 
GeneralRegEx for this function [modified] Pin
Anthony Urwin8-Sep-10 1:24
memberAnthony Urwin8-Sep-10 1:24 
GeneralRe: RegEx for this function [modified] Pin
Member 416585117-Apr-14 4:24
memberMember 416585117-Apr-14 4:24 
QuestionDecimals? Pin
smcirish13-Jan-10 4:06
membersmcirish13-Jan-10 4:06 
AnswerRe: Decimals? Pin
Canny Brisk1-Sep-13 21:47
professionalCanny Brisk1-Sep-13 21:47 
GeneralYes yes yes Pin
L C D8-Dec-08 16:04
memberL C D8-Dec-08 16:04 
GeneralRe: Yes yes yes Pin
Dush Abe26-Jun-13 13:03
memberDush Abe26-Jun-13 13:03 
GeneralAnother way A one-liner too :) Pin
Husko25-Mar-08 11:00
memberHusko25-Mar-08 11:00 
Questionhow to check if string is int and return boolean Pin
max_dev2006@yahoo.com11-Oct-06 23:58
membermax_dev2006@yahoo.com11-Oct-06 23:58 
AnswerRe: how to check if string is int and return boolean Pin
Ghecco17-Oct-06 6:31
memberGhecco17-Oct-06 6:31 
GeneralRe: how to check if string is int and return boolean Pin
tfaiz20-Jun-11 23:29
membertfaiz20-Jun-11 23:29 
GeneralWorking for me Pin
ThisTrain7-Mar-06 6:29
memberThisTrain7-Mar-06 6:29 
GeneralGood Thinking Pin
ThisTrain7-Mar-06 6:17
memberThisTrain7-Mar-06 6:17 
GeneralNo, no, no Pin
norm.net7-Mar-06 5:35
membernorm.net7-Mar-06 5:35 
GeneralRe: No, no, no Pin
Marc Brooks7-Mar-06 5:41
memberMarc Brooks7-Mar-06 5:41 
GeneralRe: No, no, no Pin
norm.net7-Mar-06 9:49
membernorm.net7-Mar-06 9:49 
GeneralRe: No, no, no Pin
norm.net7-Mar-06 9:49
membernorm.net7-Mar-06 9:49 
GeneralRe: No, no, no Pin
kingbin7-Mar-06 6:54
memberkingbin7-Mar-06 6:54 
GeneralRe: No, no, no Pin
norm.net7-Mar-06 9:49
membernorm.net7-Mar-06 9:49 
GeneralRe: No, no, no Pin
cerberiukas14-Mar-06 5:25
membercerberiukas14-Mar-06 5:25 
AnswerRe: No, no, no Pin
Leon Kovach18-Mar-06 23:57
memberLeon Kovach18-Mar-06 23:57 
GeneralRe: No, no, no Pin
dave78638313-Aug-07 8:30
memberdave78638313-Aug-07 8:30 

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