我需要转换为标题案例如下：
短语中的第一个单词;
换句话说，在同一个短语中，长度大于minLength。
我在看ToTitleCase，但结果不是预期的。
因此minLength = 2的短语“汽车非常快”将成为“汽车非常好” 快”。
我能够使用以下方法将第一个单词设为大写：
Char[] letters = source.ToCharArray();
letters[0] = Char.ToUpper(letters[0]);
并获得我正在使用的字词：
Regex.Matches(source, @"\b(\w|['-])+\b"
但我不知道如何把所有这些放在一起
谢谢你， 米格尔
答案 0 :(得分：5)
示例代码：
string input = "i have the car which is very fast";
int minLength = 2;
string regexPattern = string.Format(@"^\w|\b\w(?=\w{{{0}}})", minLength);
string output = Regex.Replace(input, regexPattern, m => m.Value.ToUpperInvariant());
更新（对于单个字符串中有多个句子的情况）。
string input = "i have the car which is very fast. me is slow.";
int minLength = 2;
string regexPattern = string.Format(@"(?<=(^|\.)\s*)\w|\b\w(?=\w{{{0}}})", minLength);
string output = Regex.Replace(input, regexPattern, m => m.Value.ToUpperInvariant());
输出：
I Have The Car Which is Very Fast. Me is Slow.
您可能希望处理!，?和其他符号，然后您可以使用以下内容。您可以根据需要添加任意数量的句子终止符号。
string input = "i have the car which is very fast! me is slow.";
int minLength = 2;
string regexPattern = string.Format(@"(?<=(^|[.!?])\s*)\w|\b\w(?=\w{{{0}}})", minLength);
string output = Regex.Replace(input, regexPattern, m => m.Value.ToUpperInvariant());
更新（2） - 将e-marketing转换为E-Marketing（将-视为有效的单词符号）：
string input = "i have the car which is very fast! me is slow. it is very nice to learn e-marketing these days.";
int minLength = 2;
string regexPattern = string.Format(@"(?<=(^|[.!?])\s*)\w|\b\w(?=[-\w]{{{0}}})", minLength);
string output = Regex.Replace(input, regexPattern, m => m.Value.ToUpperInvariant());
答案 1 :(得分：1)
英文标题案例非常复杂。它不可计算。周期。
您可以获得的最佳效果是根据您的偏好列表更改所有小词的例程。对于所有口头表达，这仍然是错误。虽然扩展的变体列表可以捕获其中的许多变体，但如果没有语义分析，有些变体仍然无法确定。两个例子：
后者从上下文中确实清楚;前者不是。意义明显不同，但计算机无法确定哪个是正确的。
（甚至人类也可以这样做。我在这里问了第一个例子StackExchnge论坛并得不到可接受的答案..）
这是我喜欢的替换列表;但是一些四个字母的单词（没有双关语）是个人选择。还有一些人可能认为所有类型的数字，例如任何，所有，少数应该大写。
这不过是优雅的，实际上它是一种各种各样的尴尬。但它对我很有用，所以我经常使用它并通过它喂了100k +标题..：
public string ETC(string title)
{ // english title capitalization
if (title == null) return "";
string s = title.Trim().Replace('`', '\''); // change apo to tick mark
TextInfo UsaTextInfo = new CultureInfo("en-US", false).TextInfo;
s = UsaTextInfo.ToTitleCase(s); // caps for all words
// a list of exceptions one way or the other..
s = s.Replace(" A ", " a ");
s = s.Replace(" also ", " Also ");
s = s.Replace(" An ", " an ");
s = s.Replace(" And ", " and ");
s = s.Replace(" as ", " As ");
s = s.Replace(" At ", " at ");
s = s.Replace(" be ", " Be ");
s = s.Replace(" But ", " But ");
s = s.Replace(" By ", " by ");
s = s.Replace(" For ", " for ");
s = s.Replace(" From ", " from ");
s = s.Replace(" if ", " If ");
s = s.Replace(" In ", " in ");
s = s.Replace(" Into ", " into ");
s = s.Replace(" he ", " He ");
s = s.Replace(" has ", " Has ");
s = s.Replace(" had ", " Had ");
s = s.Replace(" is ", " Is ");
s = s.Replace(" my ", " My ");
s = s.Replace(" ", " "); // no triple spaces
s = s.Replace("'N'", "'n'"); // Rock 'n' Roll
s = s.Replace("'N'", "'n'"); // Rock 'n Roll
s = s.Replace(" no ", " No ");
s = s.Replace(" Nor ", " nor ");
s = s.Replace(" Not ", " not ");
s = s.Replace(" Of ", " of ");
s = s.Replace(" Off ", " off ");
s = s.Replace(" On ", " on ");
s = s.Replace(" Onto ", " onto ");
s = s.Replace(" Or ", " or ");
s = s.Replace(" O'c ", " O'C ");
s = s.Replace(" Over ", " over ");
s = s.Replace(" so ", " So ");
s = s.Replace(" To ", " to ");
s = s.Replace(" that ", " That ");
s = s.Replace(" this ", " This ");
s = s.Replace(" thus ", " Thus ");
s = s.Replace(" The ", " the ");
s = s.Replace(" Too ", " too ");
s = s.Replace(" when ", " When ");
s = s.Replace(" With ", " with ");
s = s.Replace(" Up ", " up ");
s = s.Replace(" Yet ", " yet ");
// a few(!) verbal expressions
s = s.Replace(" Get up ", " Get Up ");
s = s.Replace(" Give up ", " Give Up ");
s = s.Replace(" Givin' up ", " Givin' Up ");
s = s.Replace(" Grow up ", " Grow Up ");
s = s.Replace(" Hung up ", " Hung Up ");
s = s.Replace(" Make up ", " Make Up ");
s = s.Replace(" Wake Me up ", " Wake Me Up ");
s = s.Replace(" Mixed up ", " Mixed Up ");
s = s.Replace(" Shut up ", " Shut Up ");
s = s.Replace(" Stand up ", " Stand Up ");
s = s.Replace(" Wind up ", " Wind Up ");
s = s.Replace(" Wake up ", " Wake Up ");
s = s.Replace(" Come up ", " Come Up ");
s = s.Replace(" Working on ", " Working On ");
s = s.Replace(" Waiting on ", " Waiting On ");
s = s.Replace(" Turn on ", " Turn On ");
s = s.Replace(" Move on ", " Move On ");
s = s.Replace(" Keep on ", " Keep On ");
s = s.Replace(" Bring It on ", " Bring It On ");
s = s.Replace(" Hold on ", " Hold On ");
s = s.Replace(" Hang on ", " Hang On ");
s = s.Replace(" Go on ", " Go On ");
s = s.Replace(" Coming on ", " Coming On ");
s = s.Replace(" Come on ", " Come On ");
s = s.Replace(" Call on ", " Call On ");
s = s.Replace(" Trust in ", " Trust In ");
s = s.Replace(" Fell in ", " Fell In ");
s = s.Replace(" Falling in ", " Falling In ");
s = s.Replace(" Fall in ", " Fall In ");
s = s.Replace(" Faith in ", " Faith In ");
s = s.Replace(" Come in ", " Come In ");
s = s.Replace(" Believe in ", " Believe In ");
return s.Trim();
}
请注意，仍然有很多规则无法像这样实施。
一些基本规则并不那么难：将第一个和最后一个词大写。所有动词（是），形容词（红色），promouns（他），名词（ Ace ）和数字（一个），即使它们少于3（或4）个字母。
但是例外很难，例如：当他们是一部分或者强烈的言语表达时，不要把介词大都化。 ...
示例1：＆＃39;在建筑物上工作＆＃39; - 你必须知道这是一首福音歌曲，以确定它是“开启”。
示例2：＆＃39;运行On / on Empty＆＃39;。可能意味着＆＃39; Running On＆＃39;或者＆＃39;运行（带有气体指示器）＆＃39;在空＆＃39;。
所以最后你将不得不忍受妥协。
答案 2 :(得分：0)
一个不需要正则表达式的替代（和天真）解决方案是使用String.Split方法和List.Select函数来映射复杂条件：
var text = @"i have the car which is very fast. me is slow.";
var length = 2;
var first = true; // first word in the sentence
var containsDot = false; // previous word contains a dot
var result = text
.Split(' ')
.ToList()
.Select (p =>
{
if (first)
{
p = FirstCharToUpper(p);
first = false;
}
if (containsDot)
{
p = FirstCharToUpper(p);
containsDot = false;
}
containsDot = p.Contains(".");
if (p.Length > length)
{
return FirstCharToUpper(p);
}
return p;
})
.Aggregate ((h, t) => h + " " + t);
Console.WriteLine(result);
输出结果为：
I Have The Car Which is Very Fast. Me is Slow.
FirstCharToUpper方法来自此SO post：
public static string FirstCharToUpper(string input)
{
if (String.IsNullOrEmpty(input))
throw new ArgumentException("ARGH!");
return input.First().ToString().ToUpper() + String.Join("", input.Skip(1));
}
此解决方案的缺点：条件越复杂，select语句就越复杂/不可读，但它是正则表达式的替代方案。
答案 3 :(得分：0)
这是一种使用StringBuilder和纯字符串方法的方法，不需要使用正则表达式，所以它应该非常有效：
public static string ToTitleCase(string input, int minLength = 0)
{
TextInfo ti = CultureInfo.CurrentCulture.TextInfo;
string titleCaseDefault = ti.ToTitleCase(input);
if (minLength == 0)
return titleCaseDefault;
StringBuilder sb = new StringBuilder(titleCaseDefault.Length);
int wordCount = 0;
char[] wordSeparatorChars = " \t\n.,;-:".ToCharArray();
for (int i = 0; i < titleCaseDefault.Length; i++)
{
char c = titleCaseDefault[i];
bool nonSpace = !char.IsWhiteSpace(c);
if (nonSpace)
{
wordCount++;
int firstSpace = titleCaseDefault.IndexOfAny(wordSeparatorChars, i);
int endIndex = firstSpace >= 0 ? firstSpace : titleCaseDefault.Length;
string word = titleCaseDefault.Substring(i, endIndex - i);
if (wordCount == 1) // first word upper
sb.Append(word);
else
sb.Append(word.Length < minLength ? word.ToLower() : ti.ToTitleCase(word));
i = endIndex - 1;
}
else
sb.Append(c);
}
return sb.ToString();
}
您采样数据：
string text = "the car is very fast";
string output = ToTitleCase(text, 3);