可参考微软。VisualBasic(也处理大写字符串):

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

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);
}

下面是这个问题的解决方案……

CultureInfo cultureInfo = Thread.CurrentThread.CurrentCulture;
TextInfo textInfo = cultureInfo.TextInfo;
string txt = textInfo.ToTitleCase(txt);

对于那些想要自动按下键盘的人，我用下面的VB代码做到了。NET在一个自定义文本框控件上-你显然也可以用一个普通的文本框来做-但是我喜欢通过自定义控件为特定控件添加循环代码的可能性，它适合OOP的概念。

Imports System.Windows.Forms
Imports System.Drawing
Imports System.ComponentModel

Public Class MyTextBox
    Inherits System.Windows.Forms.TextBox
    Private LastKeyIsNotAlpha As Boolean = True
    Protected Overrides Sub OnKeyPress(e As KeyPressEventArgs)
        If _ProperCasing Then
            Dim c As Char = e.KeyChar
            If Char.IsLetter(c) Then
                If LastKeyIsNotAlpha Then
                    e.KeyChar = Char.ToUpper(c)
                    LastKeyIsNotAlpha = False
                End If
            Else
                LastKeyIsNotAlpha = True
            End If
        End If
        MyBase.OnKeyPress(e)
End Sub
    Private _ProperCasing As Boolean = False
    <Category("Behavior"), Description("When Enabled ensures for automatic proper casing of string"), Browsable(True)>
    Public Property ProperCasing As Boolean
        Get
            Return _ProperCasing
        End Get
        Set(value As Boolean)
            _ProperCasing = value
        End Set
    End Property
End Class

试试这个:

string myText = "a Simple string";

string asTitleCase =
    System.Threading.Thread.CurrentThread.CurrentCulture.TextInfo.
    ToTitleCase(myText.ToLower());

如前所述，使用TextInfo。ToTitleCase可能不会给您想要的确切结果。如果你需要更多的输出控制，你可以这样做:

IEnumerable<char> CharsToTitleCase(string s)
{
    bool newWord = true;
    foreach(char c in s)
    {
        if(newWord) { yield return Char.ToUpper(c); newWord = false; }
        else yield return Char.ToLower(c);
        if(c==' ') newWord = true;
    }
}

然后像这样使用它:

var asTitleCase = new string( CharsToTitleCase(myText).ToArray() );

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