vb中大小写的转换

[haolly]

一个文本框，一个按钮，在文本框中输入英文字符，按下按钮，将大写转换成小写，小写转换成大写
如输入HellO，WolD！
转换成hELLo，wOLd！
代码怎么写？

[Missa]

把字符串转成char数组.
先判断当前字母是大写还是小写.如果是大写,就变成小写.否则就变大写.

[haolly]

[Quote=引用 1 楼 missa 的回复:]
把字符串转成char数组.
先判断当前字母是大写还是小写.如果是大写,就变成小写.否则就变大写.
[/Quote]
dim chartxt as string
chartxt=char(textbox1.text)
?????????????
然后呢？怎么判断当前字母是大写还是小写?

[兔子-顾问]

Sub Main()
	Dim s As String = "HellO，WolD！"
	Dim result As String = New String((From c In s Select IIf(Char.IsLower(c), _
															  Char.ToUpper(c), _
															  Char.ToLower(c))).Cast(Of Char).ToArray(), 0, s.Length)
	Console.WriteLine(result)
	Console.ReadKey()
End Sub

[caoqinghua]

    Sub Main()
        '定义字符串
        Dim oldstr() As Char = "HellO，WolD！".ToCharArray
        Dim newstr As String = ""
        For Each c As Char In oldstr
            '判断是否是字符
            If Char.IsLetter(c) = True Then
                If Char.IsLower(c) = True Then
                    '专大写
                    newstr += Char.ToUpper(c)
                Else
                    '专小写
                    newstr += Char.ToLower(c)
                End If
            Else
                newstr += c
            End If
        Next
        '输出新字符串
        Console.WriteLine(newstr)
    End Sub