Visual studio 2010 如何在VB中正确声明?
我是VB新手。我读一本书并遵循它的规则Visual studio 2010 如何在VB中正确声明?,visual-studio-2010,vba,Visual Studio 2010,Vba,我是VB新手。我读一本书并遵循它的规则 Public Class Form1 Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click Dim Wrap As String Wrap = Chr(13) & Chr(10) Dim i As Integer For i = 1 To 4 PictureBox
Public Class Form1
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
Dim Wrap As String
Wrap = Chr(13) & Chr(10)
Dim i As Integer
For i = 1 To 4
PictureBox1.Image = System.Drawing.Image.FromFile("C:\face0" & i & ".ico")
MsgBox("Click for next face")
Next
End Sub
End Class
它起作用了。但是,我尝试调整代码,使Wrap成为整个form1可用的变量。我做了以下操作,但它不起作用。为什么?
Public Class Form1
Dim Wrap As String
Wrap = Chr(13) & Chr(10)
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
Dim i As Integer
For i = 1 To 4
PictureBox1.Image = System.Drawing.Image.FromFile("C:\face0" & i & ".ico")
MsgBox("Click for next face")
Next
End Sub
End Class
在类级别不能有任意代码段
Wrap=Chr(13)&Chr(10)
是一段任意代码
如果要为变量赋值,请使用初始值设定项:
Dim Wrap As String = Chr(13) & Chr(10)
更好的方法是使用
ControlChars.CrLf
,这是一个预定义的常量。因为您将代码放在函数之外,所以这里只允许声明
顺便说一句,Chr(13)和Chr(10)可以通过一个更好的版本进行关联:vbCrLf
它是一个常数,所以你不需要声明它,它的作用完全相同