老派：

string oldText = "   1 2  3   4    5     ";
string newText = oldText
                    .Replace("  ", " " + (char)22 )
                    .Replace( (char)22 + " ", "" )
                    .Replace( (char)22 + "", "" );

Assert.That( newText, Is.EqualTo( " 1 2 3 4 5 " ) );

您可以简单地在一行解决方案中做到这一点!

string s = "welcome to  london";
s.Replace(" ", "()").Replace(")(", "").Replace("()", " ");

如果喜欢，可以选择其他括号(甚至其他字符)。

没有Regex，没有Linq…删除开头和结尾空格，并将任何嵌入的多个空格段减少为一个空格

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

结果:“0 1 2 3 4 5”

混合StringBuilder和Enumerable.Aggregate()作为字符串的扩展方法:

using System;
using System.Linq;
using System.Text;

public static class StringExtension
{
    public static string CondenseSpaces(this string s)
    {
        return s.Aggregate(new StringBuilder(), (acc, c) =>
        {
            if (c != ' ' || acc.Length == 0 || acc[acc.Length - 1] != ' ')
                acc.Append(c);
            return acc;
        }).ToString();
    }

    public static void Main()
    {
        const string input = "     (five leading spaces)     (five internal spaces)     (five trailing spaces)     ";
        
        Console.WriteLine(" Input: \"{0}\"", input);
        Console.WriteLine("Output: \"{0}\"", StringExtension.CondenseSpaces(input));
    }
}

执行这个程序产生以下输出:

 Input: "     (five leading spaces)     (five internal spaces)     (five trailing spaces)     "
Output: " (five leading spaces) (five internal spaces) (five trailing spaces) "

下面的代码将所有多个空格删除为一个空格

    public string RemoveMultipleSpacesToSingle(string str)
    {
        string text = str;
        do
        {
            //text = text.Replace("  ", " ");
            text = Regex.Replace(text, @"\s+", " ");
        } while (text.Contains("  "));
        return text;
    }

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