Does C# have a String Tokenizer like Java's?

Question

I'm doing simple string input parsing and I am in need of a string tokenizer. I am new to C# but have programmed Java, and it seems natural that C# should have a string tokenizer. Does it? Where is it? How do I use it?

Answer 1

You could use String.Split method.

class ExampleClass
{
    public ExampleClass()
    {
        string exampleString = "there is a cat";
        // Split string on spaces. This will separate all the words in a string
        string[] words = exampleString.Split(' ');
        foreach (string word in words)
        {
            Console.WriteLine(word);
            // there
            // is
            // a
            // cat
        }
    }
}

For more information see Sam Allen's article about splitting strings in c# (Performance, Regex)

Answer 2

I just want to highlight the power of C#'s Split method and give a more detailed comparison, particularly from someone who comes from a Java background.

Whereas StringTokenizer in Java only allows a single delimiter, we can actually split on multiple delimiters making regular expressions less necessary (although if one needs regex, use regex by all means!) Take for example this:

str.Split(new char[] { ' ', '.', '?' })

This splits on three different delimiters returning an array of tokens. We can also remove empty arrays with what would be a second parameter for the above example:

str.Split(new char[] { ' ', '.', '?' }, StringSplitOptions.RemoveEmptyEntries)

One thing Java's String tokenizer does have that I believe C# is lacking (at least Java 7 has this feature) is the ability to keep the delimiter(s) as tokens. C#'s Split will discard the tokens. This could be important in say some NLP applications, but for more general purpose applications this might not be a problem.

Answer 3

The split method of a string is what you need. In fact the tokenizer class in Java is deprecated in favor of Java's string split method.

Answer 4

I think the nearest in the .NET Framework is

string.Split()

Answer 5

For complex splitting you could use a regex creating a match collection.

Answer 6

_words = new List<string>(YourText.ToLower().Trim('\n', '\r').Split(' ').
            Select(x => new string(x.Where(Char.IsLetter).ToArray()))); 

Or

_words = new List<string>(YourText.Trim('\n', '\r').Split(' ').
            Select(x => new string(x.Where(Char.IsLetterOrDigit).ToArray()))); 

Answer 7

use Regex.Split(string,"#|#");

Answer 8

read this, split function has an overload takes an array consist of seperators http://msdn.microsoft.com/en-us/library/system.stringsplitoptions.aspx

Answer 9

The similar to Java's method is:

Regex.Split(string, pattern);

where

• string - the text you need to split
• pattern - string type pattern, what is splitting the text

Answer 10

If you're trying to do something like splitting command line arguments in a .NET Console app, you're going to have issues because .NET is either broken or is trying to be clever (which means it's as good as broken). I needed to be able to split arguments by the space character, preserving any literals that were quoted so they didn't get split in the middle. This is the code I wrote to do the job:

private static List<String> Tokenise(string value, char seperator)
{
    List<string> result = new List<string>();
    value = value.Replace("  ", " ").Replace("  ", " ").Trim();
    StringBuilder sb = new StringBuilder();
    bool insideQuote = false;
    foreach(char c in value.ToCharArray())
    {
        if(c == '"')
        {
            insideQuote = !insideQuote;
        }
        if((c == seperator) && !insideQuote)
        {
            if (sb.ToString().Trim().Length > 0)
            {
                result.Add(sb.ToString().Trim());
                sb.Clear();
            }
        }
        else
        {
            sb.Append(c);
        }
    }
    if (sb.ToString().Trim().Length > 0)
    {
        result.Add(sb.ToString().Trim());
    }

    return result;
}

Answer 11

If you are using C# 3.5 you could write an extension method to System.String that does the splitting you need. You then can then use syntax:

string.SplitByMyTokens();

More info and a useful example from MS here http://msdn.microsoft.com/en-us/library/bb383977.aspx