MoveToEx 这个函数竟然会修改参数的值，百思不得其解
代码如下

Option Explicit

Private Declare Function MoveToEx Lib "gdi32" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long, lpPoint As Long) As Long
Private Declare Function LineTo Lib "gdi32" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long) As Long

Private Sub Command1_Click()
Dim drawhdc As Long
Dim ret As Long

    drawhdc = Me.hdc
    Debug.Print drawhdc
    
    Debug.Print MoveToEx(Me.hdc, 10, 10, 0&)
    Debug.Print LineTo(Me.hdc, 100, 10)

    Debug.Print MoveToEx(drawhdc, 10, 10, 0&)
    Debug.Print drawhdc
    Debug.Print LineTo(drawhdc, 10, 100)

    Me.Refresh
End Sub

打印的结果：
 1593906163
 1
 1
 1
 10
 0
可以看到drawhdc已经从 1593906163被修改为10，导致最后一次LineTo函数的调用失败。
如果 一直用Me.hdc做参数的话，有时会导致vb的崩溃，无法捕捉任何错误信息。

更加奇怪的事情是，如果在Dim drawhdc As Long 后面再声明一个变量Dim ret As Long，那就完全正确了。

崩溃啊

MoveToEx(drawhdc, 10, 10,byval 0&)

谢谢