为何用vb api获取的窗口标题为空，而SPY++却可以
VB中callbacke function 如下：
Public Function EnumChildProc(ByVal hwnd As Long, ByVal lParam As Long) As Long
Dim slength As Long, WndTitle As String ' title bar text length and buffer
Dim retval As Long ' return value
Dim WClass As String * 50
Static winnum As Integer ' counter keeps track of how many windows have been enumerated
winnum = winnum + 1 ' one more window enumerated....
slength = GetWindowTextLength(hwnd) + 1 ' get length of title bar text
WndTitle = Space(slength) ' make room in the buffer
retval = GetWindowText(hwnd, WndTitle, slength) ' get title bar text
GetClassName hwnd, WClass, 50
EnumChildProc = 1 ' return value of 1 means continue enumeration
End Function
结果列表在excel中，窗口句柄为66622的类可以找到，但是Title却为空
ChildWndHnd ChildWndClass ChildWndTitle
66624 TCoolBar
66626 TToolBar
66620 TCoolBar
66622 TToolBar
66618 TPanel
但是为什么SPY++中却可以找到：
retval = GetWindowText(hwnd, WndTitle, slength)
检查retval的值,看看函数执行的结果是什么.
API的调用都会有返回值,都会告诉你发生了些什么.
以上代码看不出hwnd是如�
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