How do I replace multiple spaces with a single spa

Question

How can I replace multiple spaces in a string with only one space in C#?

Example:

1 2 3  4    5

would be:

1 2 3 4 5

Answer 1

Regex can be rather slow even with simple tasks. This creates an extension method that can be used off of any string.

    public static class StringExtension
    {
        public static String ReduceWhitespace(this String value)
        {
            var newString = new StringBuilder();
            bool previousIsWhitespace = false;
            for (int i = 0; i < value.Length; i++)
            {
                if (Char.IsWhiteSpace(value[i]))
                {
                    if (previousIsWhitespace)
                    {
                        continue;
                    }

                    previousIsWhitespace = true;
                }
                else
                {
                    previousIsWhitespace = false;
                }

                newString.Append(value[i]);
            }

            return newString.ToString();
        }
    }

It would be used as such:

string testValue = "This contains     too          much  whitespace."
testValue = testValue.ReduceWhitespace();
// testValue = "This contains too much whitespace."

Answer 2

Another approach which uses LINQ:

 var list = str.Split(' ').Where(s => !string.IsNullOrWhiteSpace(s));
 str = string.Join(" ", list);

Answer 3

myString = Regex.Replace(myString, " {2,}", " ");

Answer 4

no Regex, no Linq... removes leading and trailing spaces as well as reducing any embedded multiple space segments to one space

string myString = "   0 1 2  3   4               5  ";
myString = string.Join(" ", myString.Split(new char[] { ' ' }, 
StringSplitOptions.RemoveEmptyEntries));

result:"0 1 2 3 4 5"

Answer 5

I know this is pretty old, but ran across this while trying to accomplish almost the same thing. Found this solution in RegEx Buddy. This pattern will replace all double spaces with single spaces and also trim leading and trailing spaces.

pattern: (?m:^ +| +$|( ){2,})
replacement: $1

Its a little difficult to read since we're dealing with empty space, so here it is again with the "spaces" replaced with a "_".

pattern: (?m:^_+|_+$|(_){2,})  <-- don't use this, just for illustration.

The "(?m:" construct enables the "multi-line" option. I generally like to include whatever options I can within the pattern itself so it is more self contained.

Answer 6

string xyz = "1   2   3   4   5";
xyz = string.Join( " ", xyz.Split( new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries ));