Check for special characters - in a string

Question

How do I check a string to make sure it contains numbers  letters  or space only

User · Answer

string s      KUH  I   OFNlkfn    var withoutSpecial   new string s Where c   gt  Char IsLetterOrDigit c                                                  Char IsWhiteSpace c   ToArray      if  s    withoutSpecial        Console WriteLine  String contains special chars

User · Answer

Try this way   public static bool hasSpecialChar string input                string specialChar            amp                     -   lt  gt              foreach  var item in specialChar                        if  input Contains item   return true                     return false

User · Answer

While there are many ways to skin this cat  I prefer to wrap such code into reusable extension methods that make it trivial to do going forward   When using extension methods  you can also avoid RegEx as it is slower than a direct character check   I like using the extensions in the Extensions cs NuGet package   It makes this check as simple as   Add the  https   www nuget org packages Extensions cs  1  package to your project  Add  quot using Extensions  quot  to the top of your code   quot smith23  quot  IsAlphaNumeric   will return False whereas  quot smith23 quot  IsAlphaNumeric   will return True   By default the  IsAlphaNumeric   method ignores spaces  but it can also be overridden such that  quot smith 23 quot  IsAlphaNumeric false  will return False since the space is not considered part of the alphabet  Every other check in the rest of the code is simply MyString IsAlphaNumeric

User · Answer

A great way using C  and Linq here   public static bool HasSpecialCharacter this string s        foreach  var c in s                if  char IsLetterOrDigit c                         return true                      return false       And access it like this    myString HasSpecialCharacter

User · Answer

You could do it with a bool  I ve been learning recently and found I could do it this way  In this example  I m checking a user s input to the console   using System  using System Linq   namespace CheckStringContent       class Program               static void Main string   args                          Get a password to check             Console WriteLine  Please input a Password                  string userPassword   Console ReadLine                   Check the string             bool symbolCheck   userPassword Any p   gt   char IsLetterOrDigit p                   Write results to console             Console WriteLine   Symbols are present   symbolCheck                              This returns  True  if special chars  symbolCheck  are present in the string  and  False  if not present

User · Answer

Use the regular Expression below in to validate a string to make sure it contains numbers  letters  or space only    a-zA-Z0-9

User · Answer

String test string    tesintg  234524     if  System Text RegularExpressions Regex IsMatch test string     a-zA-Z0-9 x20              Good-to-go     An example can be found here  http   ideone com B1HxA

User · Answer

The easiest way it to use a regular expression    Regular Expression for alphanumeric and underscores  Using regular expressions in  net    http   www regular-expressions info dotnet html  MSDN Regular Expression  Regex IsMatch  var regexItem   new Regex    a-zA-Z0-9         if regexItem IsMatch YOUR STRING

User · Answer

If the list of acceptable characters is pretty small  you can use a regular expression like this   Regex IsMatch items    a-z0-9      RegexOptions IgnoreCase     The regular expression used here looks for any character from a-z and 0-9 including a space  what s inside the square brackets      that there is one or more of these characters  the   sign--you can use a   for 0 or more    The final option tells the regex parser to ignore case   This will fail on anything that is not a letter  number  or space   To add more characters to the blessed list  add it inside the square brackets

User · Answer

Simple   function HasSpecialChars string yourString        return yourString Any  ch   gt    Char IsLetterOrDigit  ch

[c#] Check for special characters (/*-+_@&$#%) in a string?

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