Need regex (using C#) to condense all whitepace into single whitespaces

Question

I need to replace multiple whitespaces into a single whitespace (per iteration) in a document. Doesn't matter whether they are spaces, tabs or newlines, any combination of any kind of whitespace needs to be truncated to a single whitespace.

Let's say we have the string: "Hello,\t \t\n \t \n world", (where \t and \n represent tabs and newlines respectively) then I'd need it to become "Hello, world".

I'm so completely bewildered by regex more generally that I ended up just asking.

Considerations:

I have no control over the document, since it could be any document on the internet.
I'm using C#, so if anyone knows how to do this in C# specifically, that would be even more awesome.
I don't really have to use regex (before someone asks), but I figured it's probably the optimal way, since regex is designed for this sort of stuff, and my own strpos/str_replace/substr soup would probably not perform as well. Performance is important on this one so what I'm essentially looking for is an efficient way to do this to any random text file on the internet (remember, I can't predict the size!).

Thanks in advance!

womp · Accepted Answer · 2009-12-22 17:22:11Z

11

newString = Regex.Replace(oldString, @"\s+", " ");

The "\s" is a regex character class for any whitespace character, and the + means "one or more". It replaces each occurence with a simple space character.

answered Dec 22, 2009 at 17:22

womp

117k27 gold badges240 silver badges271 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Community · Accepted Answer · 2017-05-23 12:07:05Z

4

You may find this SO answer useful:

How do I replace multiple spaces with a single space in C#?

Adapting the answer to also replace tabs and newlines as well is relatively straight forward:

RegexOptions options = RegexOptions.None;
Regex regex = new Regex(@"\s+", options);     
tempo = regex.Replace(tempo, @" ");

edited May 23, 2017 at 12:07

CommunityBot

11 silver badge

answered Dec 22, 2009 at 17:21

LBushkin

132k33 gold badges218 silver badges265 bronze badges

2 Comments

TLiebe Over a year ago

Check out the answer by Matt in the above link as the accepted solution looks like it only replaces the space character, not newlines and tabs. The '\s' in the pattern is what tells it to match on any whitespace character.

Teekin Over a year ago

I looked before I asked, I swear, I looked! Thanks a bunch, that helped me out. :)

to StackOverflow · Accepted Answer · 2009-12-22 17:39:01Z

As someone who sympathizes with Jamie Zawinski's position on Regex, I'll offer an alternative for what it's worth.

Not wanting to be religious about it, but I'd say it's faster than Regex, though whether you'll ever be processing strings long enough to see the difference is another matter.

    public static string CompressWhiteSpace(string value)
    {
        if (value == null) return null;

        bool inWhiteSpace = false;
        StringBuilder builder = new StringBuilder(value.Length);

        foreach (char c in value)
        {
            if (Char.IsWhiteSpace(c))
            {
                inWhiteSpace = true;
            }
            else
            {
                if (inWhiteSpace) builder.Append(' ');
                inWhiteSpace = false;
                builder.Append(c);
            }
        }
        return builder.ToString();
    }

Woot4Moo · Accepted Answer · 2009-12-22 17:24:05Z

0

I would suggest you replace your chomp with
 $line =~ s/\s+$//;

which will strip off all trailing white spaces - tabs, spaces, new lines and returns as well.

Taken from: http://www.wellho.net/forum/Perl-Programming/New-line-characters-beware.html

I'm aware its Perl, but it should be helpful enough for you.

answered Dec 22, 2009 at 17:24

Woot4Moo

24.4k19 gold badges103 silver badges156 bronze badges

Comments

tvanfosson · Accepted Answer · 2009-12-22 17:43:12Z

Actually I think an extension method would probably be more efficient as you don't have the state machine overhead of the regex. Essentially, it becomes a very specialized pattern matcher.

public static string Collapse( this string source )
{
    if (string.IsNullOrEmpty( source ))
    {
        return source;
    }

    StringBuilder builder = new StringBuilder();
    bool inWhiteSpace = false;
    bool sawFirst = false;
    foreach (var c in source)
    {
        if (char.IsWhiteSpace(c))
        {
            inWhiteSpace = true;
        }
        else
        {
            // only output a whitespace if followed by non-whitespace
            // except at the beginning of the string
            if (inWhiteSpace && sawFirst)
            {
                builder.Append(" ");
            }
            inWhiteSpace = false;
            sawFirst = true;
            builder.Append(c);
        }
    }
    return builder.ToString();
}

Collectives™ on Stack Overflow

Need regex (using C#) to condense all whitepace into single whitespaces

5 Answers 5

Comments

2 Comments

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

2 Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related