求教自己写的小程序（就三行）怎么能运行但不起作用

Question

1个窗口，1个按钮：
Private Sub Command1_Click()
SendMessage FindWindow(0&, "无标题 - 记事本"), WM_KEYDOWN, VK_F5, 0&
End Sub
1个模块：
Public Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long

Public Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByValwMsg As Long, ByVal wParam As Long, lParam As Any) As Long

可以运行，但是出不来结果，哪里错了？

Answer 1

应该是向记事本的文本框发送消息，F5是向文本框发送的，目标是文本框的句柄，修改如下：

模块代码：
Public Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Public Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long
Public Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Public Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Public Const WM_KEYDOWN = &H100
Public Const VK_F5 = &H74

窗体代码：
Private Sub Command1_Click()
Dim hwnd As Long, h As Long
hwnd = FindWindow(vbNullString, "无标题 - 记事本")
h = FindWindowEx(hwnd, 0, "Edit", vbNullString)
PostMessage h, WM_KEYDOWN, VK_F5, 0& '按下F5键
End Sub

追问

yes！出结果了

有2个地方我不明白：
PostMessage 和SendMessage 是否只写1个就行？
为什么要写这2句？：
Public Const WM_KEYDOWN = &H100
Public Const VK_F5 = &H74

追答

似乎不能用SendMessage，具体两个函数区别我说不清，你可以在网上自己查
写那两句，是因为要声明常量，不声明的话，系统默认把它当变量，默认值是0，那当然就不对了

追问

怎么追问不显示

Answer 2

因为你没有定义,应在模块里定义 public const VK_F5=116，就好了。我是vb编程团队成员，多多指教。如果正确，请采纳。

追问

谢了，因为楼上是先说的，所以采纳要给他，不好意思啊