CODEWITHSUNDEEP
c#regex
Valerio
Valerio

Reputation: 3617

Regex to exclude all chars except letters

I'm a real regex n00b so I ask your help: I need a regex witch match only letters and numbers and exclude punctations, non ascii characters and spaces.

"ilikestackoverflow2012" would be a valid string.

"f### you °§è" not valid.

"hello world" not valid

"hello-world" and "*hello_world*" not valid

and so on.

I need it to make a possibly complex business name url friendly.

Thanks in advance!

Upvotes: 3

Views: 4486

Answers (7)

Sk93
Sk93

Reputation: 3718

^[0-9a-zA-Z]+$

Matches one or more alphanumeric characters with no spaces or non-alpha characters.

Upvotes: 2

Vaman Kulkarni
Vaman Kulkarni

Reputation: 3451

You can use below regex.

^[a-zA-Z0-9]+$

Upvotes: 2

Mark Byers
Mark Byers

Reputation: 838216

To validate a string you can use the following regular expression with Regex.IsMatch:

"^[0-9A-Za-z]+$"

Explanation:

  • ^ is a start of string anchor.
  • [...] is a character class.
  • + means one or more.
  • $ is an end of string anchor.

I need it to make a possibly complex business name url friendly

Then you want to replace the characters that don't match. Use Regex.Replace with the following regular expression:

"[^0-9A-Za-z]+"

Explanation:

  • [^...] is a negated character class.

Code:

string result = Regex.Replace(input, "[^0-9A-Za-z]+" , "");

See it working online: ideone

Note that different business names could give the same resulting string. For example, businesses whose names contain only Chinese characters will all give the empty string.

Upvotes: 2

L.B
L.B

Reputation: 116118

You don't need regex for this.

string s = "......"
var isValid = s.All(Char.IsLetterOrDigit);

-

I need it to make a possibly complex business name url friendly

You can also use HttpUtility.UrlEncode

var urlFriendlyString = HttpUtility.UrlEncode(yourString);

Upvotes: 2

Marcelo De Zen
Marcelo De Zen

Reputation: 9497

Try this:

var regex = new Regex(@"^[a-zA-Z0-9]+$");
var test = new[] {"ilikestack", "hello world", "hello-world", "###"};

foreach (var s in test)
   Console.WriteLine("{0}: {1}", s, regex.IsMatch(s));

EDIT: If you want something like @Andre_Miller said, you should use the same regex with Regex.Replace();

Regex.Replace(s, @"[^a-zA-Z0-9]+", "")

OR

var regex = new Regex(@"^[a-zA-Z0-9]+$");
regex.Replace("input-string-@#$@#");

Upvotes: 1

Spencer Rathbun
Spencer Rathbun

Reputation: 14900

What's wrong with [:alnum:]? It's a posix standard. So your whole regex would be: ^[:alnum:]+$.

The wikipedia article for regular expressions includes lots of examples and details.

Upvotes: 1

Jaime Torres
Jaime Torres

Reputation: 10515

Try

^[a-zA-Z0-9]+$

www.regexr.com is a GREAT resource.

Upvotes: 1

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