How can I strip punctuation from a string?

Question

For the hope-to-have-an-answer-in-30-seconds part of this question, I\'m specifically looking for C#

But in the general case, what\'s the best way to strip punctuati

Answer 1

Assuming "best" means "simplest" I suggest using something like this:

String stripped = input.replaceAll("\\p{Punct}+", "");

This example is for Java, but all sufficiently modern Regex engines should support this (or something similar).

Edit: the Unicode-Aware version would be this:

String stripped = input.replaceAll("\\p{P}+", "");

The first version only looks at punctuation characters contained in ASCII.

Answer 2

Based off GWLlosa's idea, I was able to come up with the supremely ugly, but working:

string s = "cat!";
s = s.ToCharArray().ToList<char>()
      .Where<char>(x => !char.IsPunctuation(x))
      .Aggregate<char, string>(string.Empty, new Func<string, char, string>(
             delegate(string s, char c) { return s + c; }));

Answer 3

If you want to use this for tokenizing text you can use:

new string(myText.Select(c => char.IsPunctuation(c) ? ' ' : c).ToArray())

Answer 4

For anyone who would like to do this via RegEx:

This code shows the full RegEx replace process and gives a sample Regex that only keeps letters, numbers, and spaces in a string - replacing ALL other characters with an empty string:

//Regex to remove all non-alphanumeric characters
System.Text.RegularExpressions.Regex TitleRegex = new 
System.Text.RegularExpressions.Regex("[^a-z0-9 ]+", 
System.Text.RegularExpressions.RegexOptions.IgnoreCase);

string ParsedString = TitleRegex.Replace(stringToParse, String.Empty);

return ParsedString;

Answer 5

#include<string>
    #include<cctype>
    using namespace std;

    int main(int a, char* b[]){
    string strOne = "H,e.l/l!o W#o@r^l&d!!!";
    int punct_count = 0;

cout<<"before : "<<strOne<<endl;
for(string::size_type ix = 0 ;ix < strOne.size();++ix)   
{   
    if(ispunct(strOne[ix])) 
    {
            ++punct_count;  
            strOne.erase(ix,1); 
            ix--;
    }//if
}
    cout<<"after : "<<strOne<<endl;
                  return 0;
    }//main

Answer 6

For long strings I use this:

var normalized = input
                .Where(c => !char.IsPunctuation(c))
                .Aggregate(new StringBuilder(),
                           (current, next) => current.Append(next), sb => sb.ToString());

performs much better than using string concatenations (though I agree it's less intuitive).