这个正则表达式在每个大写字母前放置一个空格字符:

using System.Text.RegularExpressions;

const string myStringWithoutSpaces = "ThisIsAStringWithoutSpaces";
var myStringWithSpaces = Regex.Replace(myStringWithoutSpaces, "([A-Z])([a-z]*)", " $1$2");

注意前面的空间，如果“$1$2”，这是可以完成的。

结果如下:

"This Is A String Without Spaces"

灵感来自@MartinBrown， 两行简单的正则表达式，它将解析您的名字，包括字符串中的任何地方的无同义词。

public string ResolveName(string name)
{
   var tmpDisplay = Regex.Replace(name, "([^A-Z ])([A-Z])", "$1 $2");
   return Regex.Replace(tmpDisplay, "([A-Z]+)([A-Z][^A-Z$])", "$1 $2").Trim();
}

这是我的:

private string SplitCamelCase(string s) 
{ 
    Regex upperCaseRegex = new Regex(@"[A-Z]{1}[a-z]*"); 
    MatchCollection matches = upperCaseRegex.Matches(s); 
    List<string> words = new List<string>(); 
    foreach (Match match in matches) 
    { 
        words.Add(match.Value); 
    } 
    return String.Join(" ", words.ToArray()); 
}

具有fold的实现，也称为Aggregate:

    public static string SpaceCapitals(this string arg) =>
       new string(arg.Aggregate(new List<Char>(),
                      (accum, x) => 
                      {
                          if (Char.IsUpper(x) &&
                              accum.Any() &&
                              // prevent double spacing
                              accum.Last() != ' ' &&
                              // prevent spacing acronyms (ASCII, SCSI)
                              !Char.IsUpper(accum.Last()))
                          {
                              accum.Add(' ');
                          }

                          accum.Add(x);

                          return accum;
                      }).ToArray());

除了请求之外，这个实现还正确地保存了开头、内部、结尾空格和首字母缩写，例如，

" SpacedWord " => " Spaced Word ",  

"Inner Space" => "Inner Space",  

"SomeACRONYM" => "Some ACRONYM".

static string AddSpacesToColumnName(string columnCaption)
    {
        if (string.IsNullOrWhiteSpace(columnCaption))
            return "";
        StringBuilder newCaption = new StringBuilder(columnCaption.Length * 2);
        newCaption.Append(columnCaption[0]);
        int pos = 1;
        for (pos = 1; pos < columnCaption.Length-1; pos++)
        {               
            if (char.IsUpper(columnCaption[pos]) && !(char.IsUpper(columnCaption[pos - 1]) && char.IsUpper(columnCaption[pos + 1])))
                newCaption.Append(' ');
            newCaption.Append(columnCaption[pos]);
        }
        newCaption.Append(columnCaption[pos]);
        return newCaption.ToString();
    }

这里有一个更彻底的解决方案，它没有在单词前面放空格:

注意:我使用了多个regex(不简洁，但它也可以处理首字母缩略词和单字母单词)

Dim s As String = "ThisStringHasNoSpacesButItDoesHaveCapitals"
s = System.Text.RegularExpressions.Regex.Replace(s, "([a-z])([A-Z](?=[A-Z])[a-z]*)", "$1 $2")
s = System.Text.RegularExpressions.Regex.Replace(s, "([A-Z])([A-Z][a-z])", "$1 $2")
s = System.Text.RegularExpressions.Regex.Replace(s, "([a-z])([A-Z][a-z])", "$1 $2")
s = System.Text.RegularExpressions.Regex.Replace(s, "([a-z])([A-Z][a-z])", "$1 $2") // repeat a second time

In:

"ThisStringHasNoSpacesButItDoesHaveCapitals"
"IAmNotAGoat"
"LOLThatsHilarious!"
"ThisIsASMSMessage"

Out:

"This String Has No Spaces But It Does Have Capitals"
"I Am Not A Goat"
"LOL Thats Hilarious!"
"This Is ASMS Message" // (Difficult to handle single letter words when they are next to acronyms.)