How to replace multiple white spaces with one white space

Question

Let's say I have a string such as:

"Hello     how are   you           doing?"

I would like a function that turns multiple spaces into one space.

So I would get:

"Hello how are you doing?"

I know I could use regex or call

string s = "Hello     how are   you           doing?".replace("  "," ");

But I would have to call it multiple times to make sure all sequential whitespaces are replaced with only one.

Is there already a built in method for this?

Answer 1

string cleanedString = System.Text.RegularExpressions.Regex.Replace(dirtyString,@"\s+"," ");

Answer 2

While the existing answers are fine, I'd like to point out one approach which doesn't work:

public static string DontUseThisToCollapseSpaces(string text)
{
    while (text.IndexOf("  ") != -1)
    {
        text = text.Replace("  ", " ");
    }
    return text;
}

This can loop forever. Anyone care to guess why? (I only came across this when it was asked as a newsgroup question a few years ago... someone actually ran into it as a problem.)

Answer 3

A regular expressoin would be the easiest way. If you write the regex the correct way, you wont need multiple calls.

Change it to this:

string s = System.Text.RegularExpressions.Regex.Replace(s, @"\s{2,}", " "); 

Answer 4

Here is the Solution i work with. Without RegEx and String.Split.

public static string TrimWhiteSpace(this string Value)
{
    StringBuilder sbOut = new StringBuilder();
    if (!string.IsNullOrEmpty(Value))
    {
        bool IsWhiteSpace = false;
        for (int i = 0; i < Value.Length; i++)
        {
            if (char.IsWhiteSpace(Value[i])) //Comparion with WhiteSpace
            {
                if (!IsWhiteSpace) //Comparison with previous Char
                {
                    sbOut.Append(Value[i]);
                    IsWhiteSpace = true;
                }
            }
            else
            {
                IsWhiteSpace = false;
                sbOut.Append(Value[i]);
            }
        }
    }
    return sbOut.ToString();
}

so you can:

string cleanedString = dirtyString.TrimWhiteSpace();