Question

试图让它改变解析后的字符串段的第一个字母的大小写。因此，如果用户在txtName中输入“JOHN WAYNE DOE”，那么它将显示“John Wayne Doe” 我按照它在书中显示它的方式输入它，但是消息框显示已解析的字符串，但是输入了所以在上面的示例中返回的是“JOHN WAYNE DOE” 我认为它是一个逻辑错误，因为我知道这样做很多只是不知道我在哪里犯了错误。

    Dim name As String = txtName.Text
    name = name.Trim
    Dim names() As String = name.Split(CChar(" "))
    Dim firstName As String = names(0)
    Dim middleName As String = names(1)
    Dim lastName As String = names(2)

    Dim firstLetters1 As String = firstName.Substring(0, 1).ToUpper
    Dim otherletters1 As String = firstName.Substring(1).ToLower

    Dim firstLetters2 As String = middleName.Substring(0, 1).ToUpper
    Dim otherletters2 As String = middleName.Substring(1).ToLower

    Dim firstletters3 As String = lastName.Substring(0, 1).ToUpper
    Dim otherletters3 As String = lastName.Substring(1).ToLower

    MessageBox.Show("First Name: " & firstName & vbCrLf & "Middle Name: " & middleName & vbCrLf & "Last Name: " & lastName)

Answer 1

提到这个替代

Dim currentCulture As CultureInfo = System.Threading.Thread.CurrentThread.CurrentCulture 
Dim titleCase = currentCulture.TextInfo.ToTitleCase(txtName.Text)
Console.WriteLine(titleCase)
Dim names() As String = titleCase.Split(" "c)
......

这种方法确保琴弦的正确套管符合当前的文化并且不需要如此多的直接拆分和字符串连接与固有的内存占用。（在内部，StringBuilder用于操作输入字符串，只有一个最终的ToString（）返回结果）

Answer 2

试试这个：

MessageBox.Show(_
    "First Name: " & firstLetters1 & otherletters1 & vbCrLf & _
    "Middle Name: " & firstLetters2 & otherletters2 & vbCrLf & _ 
    "Last Name: " & firstLetters3 & otherletters3)

String是不可变类，您的ToUpper和ToLower调用会创建新实例。在消息框中，您将传递旧的未处理实例。

<强>更新或者，您可以使用我们的旧电话：

 MessageBox.Show("First Name: " & firstName & vbCrLf & "Middle Name: " & middleName & vbCrLf & "Last Name: " & lastName)

只要你以前这样做：

firstName = firstLetters1 & otherletters1
middleName = firstLetters2 & otherletters2
lastName = firstLetters3 & otherletters3

这可以让你更好地了解字符串的不变性是如何工作的。

Answer 3

Dim Name As String = "JOHN WAYNE DOE"
Name = Microsoft.VisualBasic.StrConv(Name, VbStrConv.ProperCase)

将输出“John Wayne Doe”

在visual basic中使用toupper和tolower

3 个答案: