这就是我所使用的，它适用于大多数情况，除非用户决定通过按shift或caps lock覆盖它。比如Android和iOS键盘。

Private Class ProperCaseHandler
    Private Const wordbreak As String = " ,.1234567890;/\-()#$%^&*€!~+=@"
    Private txtProperCase As TextBox

    Sub New(txt As TextBox)
        txtProperCase = txt
        AddHandler txt.KeyPress, AddressOf txtTextKeyDownProperCase
    End Sub

    Private Sub txtTextKeyDownProperCase(ByVal sender As System.Object, ByVal e As Windows.Forms.KeyPressEventArgs)
        Try
            If Control.IsKeyLocked(Keys.CapsLock) Or Control.ModifierKeys = Keys.Shift Then
                Exit Sub
            Else
                If txtProperCase.TextLength = 0 Then
                    e.KeyChar = e.KeyChar.ToString.ToUpper()
                    e.Handled = False
                Else
                    Dim lastChar As String = txtProperCase.Text.Substring(txtProperCase.SelectionStart - 1, 1)

                    If wordbreak.Contains(lastChar) = True Then
                        e.KeyChar = e.KeyChar.ToString.ToUpper()
                        e.Handled = False
                    End If
                End If

            End If

        Catch ex As Exception
            Exit Sub
        End Try
    End Sub
End Class

下面是一个逐字符的实现。它应该和"(一二三)"一起工作：

public static string ToInitcap(this string str)
{
    if (string.IsNullOrEmpty(str))
        return str;
    char[] charArray = new char[str.Length];
    bool newWord = true;
    for (int i = 0; i < str.Length; ++i)
    {
        Char currentChar = str[i];
        if (Char.IsLetter(currentChar))
        {
            if (newWord)
            {
                newWord = false;
                currentChar = Char.ToUpper(currentChar);
            }
            else
            {
                currentChar = Char.ToLower(currentChar);
            }
        }
        else if (Char.IsWhiteSpace(currentChar))
        {
            newWord = true;
        }
        charArray[i] = currentChar;
    }
    return new string(charArray);
}

public static string PropCase(string strText)
{
    return new CultureInfo("en").TextInfo.ToTitleCase(strText.ToLower());
}

就我个人而言，我尝试了TextInfo。ToTitleCase方法，但是，我不明白为什么当所有字符都是大写的时候它不起作用。

虽然我喜欢Winston Smith提供的util函数，但让我提供我目前正在使用的函数:

public static String TitleCaseString(String s)
{
    if (s == null) return s;

    String[] words = s.Split(' ');
    for (int i = 0; i < words.Length; i++)
    {
        if (words[i].Length == 0) continue;

        Char firstChar = Char.ToUpper(words[i][0]); 
        String rest = "";
        if (words[i].Length > 1)
        {
            rest = words[i].Substring(1).ToLower();
        }
        words[i] = firstChar + rest;
    }
    return String.Join(" ", words);
}

玩一些测试字符串:

String ts1 = "Converting string to title case in C#";
String ts2 = "C";
String ts3 = "";
String ts4 = "   ";
String ts5 = null;

Console.Out.WriteLine(String.Format("|{0}|", TitleCaseString(ts1)));
Console.Out.WriteLine(String.Format("|{0}|", TitleCaseString(ts2)));
Console.Out.WriteLine(String.Format("|{0}|", TitleCaseString(ts3)));
Console.Out.WriteLine(String.Format("|{0}|", TitleCaseString(ts4)));
Console.Out.WriteLine(String.Format("|{0}|", TitleCaseString(ts5)));

给输出:

|Converting String To Title Case In C#|
|C|
||
|   |
||

可参考微软。VisualBasic(也处理大写字符串):

string properCase = Strings.StrConv(str, VbStrConv.ProperCase);

即使是驼色大小写也能正常工作:'someText in YourPage'

public static class StringExtensions
{
    /// <summary>
    /// Title case example: 'Some Text In Your Page'.
    /// </summary>
    /// <param name="text">Support camel and title cases combinations: 'someText in YourPage'</param>
    public static string ToTitleCase(this string text)
    {
        if (string.IsNullOrEmpty(text))
        {
            return text;
        }
        var result = string.Empty;
        var splitedBySpace = text.Split(new[]{ ' ' }, StringSplitOptions.RemoveEmptyEntries);
        foreach (var sequence in splitedBySpace)
        {
            // let's check the letters. Sequence can contain even 2 words in camel case
            for (var i = 0; i < sequence.Length; i++)
            {
                var letter = sequence[i].ToString();
                // if the letter is Big or it was spaced so this is a start of another word
                if (letter == letter.ToUpper() || i == 0)
                {
                    // add a space between words
                    result += ' ';
                }
                result += i == 0 ? letter.ToUpper() : letter;
            }
        }
        return result.Trim();
    }
}