使用按钮更改一个图片框中的两个图像 (VB.NET)
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Change two images in one picture box using a button (VB.NET)
提问by Exn
I've been trying to change the image in a picture box. It works if I want to change it with one image, but I can't get it to change to the other image. It should alternate between the two images when I click the button.
我一直在尝试更改图片框中的图像。如果我想用一个图像更改它，它会起作用，但我无法将它更改为另一个图像。当我单击按钮时，它应该在两个图像之间交替。
Here is my code:
这是我的代码：
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim num As Boolean
If num = False Then
PictureBox3.Image = My.Resources.Beep
num = True
Else
PictureBox3.Image = My.Resources.Skateboard
num = False
End If
End Sub
I've been trying to figure out why it doesn't work for a long time, any help wouldbe appreciated.
我一直试图弄清楚为什么它长时间不起作用，任何帮助将不胜感激。
回答by Steve
You variable numis local to the method, so you could change it how you like, but everytime this code is called the variable numis recreated and given the default initial value of False.
It will be True just from the point in which you set it to the exit of the method
您的变量num是该方法的局部变量，因此您可以根据自己的喜好更改它，但是每次调用此代码时，num都会重新创建该变量并赋予默认初始值 False。
仅从您将其设置为方法的退出点开始，它就会为 True
To resolve the problem you need to declare it Sharedor declare it outside the procedure at class global level
要解决此问题，您需要将其声明为Shared或在类全局级别的过程之外声明它
Shared option
共享选项
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim Shared num As Boolean
If num = False Then
PictureBox3.Image = My.Resources.Beep
num = True
Else
PictureBox3.Image = My.Resources.Skateboard
num = False
End If
End Sub
Class level option
班级选项
Dim num As Boolean
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
.....
End Sub
回答by syed mohsin
Your num variable is in the method so when you call your method it initializes again and again and doesn't remember what you set it(either true or false) last time. Try this.
您的 num 变量在方法中，因此当您调用您的方法时，它会一次又一次地初始化并且不记得您上次设置的内容（真或假）。尝试这个。
Dim num As Boolean
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If num = False Then
PictureBox3.Image = My.Resources.Beep
num = True
Else
PictureBox3.Image = My.Resources.Skateboard
num = False
End If
End Sub
