IsNumeric function in c

Question

I know it s possible to check whether the value of a text box or variable is numeric using try catch statements  but IsNumeric is so much simpler   One of my current projects requires recovering values from text boxes   Unfortunately  it is written in C    I understand that there s a way to enable the Visual Basic IsNumeric function in Visual C  by adding a reference to Visual Basic  though I don t know the syntax for it   What I need is a clear and concise walkthrough for enabling the IsNumeric function in C   I don t plan on using any other functions indigenous to Visual Basic

User · Answer

Using C  7   NET Framework 4 6 2  you can write an IsNumeric function as a one-liner   public bool IsNumeric string val    gt  int TryParse val  out int result     Note that the function above will only work for integers  Int32   But you can implement corresponding functions for other numeric data types  like long  double  etc

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Is numeric can be achieved via many ways  but i use my way  public bool IsNumeric string value        bool isNumeric   true      char   digits    0123456789  ToCharArray        char   letters   value ToCharArray        for  int k   0  k  lt  letters Length  k                  for  int i   0  i  lt  digits Length  i                          if  letters k     digits i                                 isNumeric   false                  break                                    return isNumeric

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I usually handle things like this with an extension method  Here is one way implemented in a console app   namespace ConsoleApplication10       class Program               static void Main string   args                        CheckIfNumeric  A                CheckIfNumeric  22                CheckIfNumeric  Potato                CheckIfNumeric  Q                CheckIfNumeric  A amp                     Console ReadLine                       private static void CheckIfNumeric string input                        if  input IsNumeric                                  Console WriteLine input     is numeric                               else                               Console WriteLine input     is NOT numeric                                        public static class StringExtensions               public static bool IsNumeric this string input                        return Regex IsMatch input      d                          Output   A is NOT numeric   22 is numeric   Potato is NOT numeric   Q is NOT numeric   A amp     is NOT numeric   Note  here are a few other ways to check for numbers using RegEx

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It is worth mentioning that one can check the characters in the string against Unicode categories - numbers  uppercase  lowercase  currencies and more  Here are two examples checking for numbers in a string using Linq   var containsNumbers   s Any Char IsNumber   var isNumber   s All Char IsNumber     For clarity  the syntax above is a shorter version of   var containsNumbers   s Any c  gt Char IsNumber c    var isNumber   s All c  gt Char IsNumber c      Link to unicode categories on MSDN   UnicodeCategory Enumeration

User · Answer

To totally steal from Bill answer you can make an extension method and use some syntactic sugar to help you out   Create a class file  StringExtensions cs  Content   public static class StringExt       public static bool IsNumeric this string text                double test          return double TryParse text  out test             EDIT  This is for updated C  7 syntax  Declaring out parameter in-line   public static class StringExt       public static bool IsNumeric this string text    gt  double TryParse text  out          Call method like such   var text    I am not a number   text IsNumeric       lt --- returns false

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Try following code snippet   double myVal   0  String myVar    Not Numeric Type    if  Double TryParse myVar   out myNum          it is a number   else        it is not a number

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http   msdn microsoft com en-us library wkze6zky aspx  menu  Project-- Add Reference   click  assemblies  framework  Put a checkmark on Microsoft VisualBasic   Hit OK   That link is for Visual Studio 2013  you can use the  Other versions  dropdown for different versions of visual studio   In all cases you need to add a reference to the  NET assembly  Microsoft VisualBasic    At the top of your c  file you neeed   using Microsoft VisualBasic    Then you can look at writing the code   The code would be something like      private void btnOK Click object sender  EventArgs e             if   Information IsNumeric startingbudget                     MessageBox Show  This is a number

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public bool IsNumeric string value        return value All char IsNumber

User · Answer

You could make a helper method  Something like   public bool IsNumeric string input        int test      return int TryParse input  out test

[c#] IsNumeric function in c#

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