WaitForSingleObject这个API使用时的一个问题

[jediknight]

re = WaitForSingleObject(ProcHandle,100);
Application->ProcessMessage();//这句很重要,向系统发送消息,不至于系统当机
这时C++程序段,使用了WaitForSingleObject函数后,调用了ProcessMessage函数,有资料说是如不调用ProcessMessage函数,系统将只运行这段程序而不会运行其他程序了.
现在问题是在VB中调用了WaitForSingleObject后CPU占用100%,请问该怎么解决呢？

[道素]

试试这个例子:
'This program needs a common dialog box, named CDBox

Const INFINITE = &HFFFF
Const STARTF_USESHOWWINDOW = &H1
Private Enum enSW
SW_HIDE = 0
SW_NORMAL = 1
SW_MAXIMIZE = 3
SW_MINIMIZE = 6
End Enum
Private Type PROCESS_INFORMATION
hProcess As Long
hThread As Long
dwProcessId As Long
dwThreadId As Long
End Type
Private Type STARTUPINFO
cb As Long
lpReserved As String
lpDesktop As String
lpTitle As String
dwX As Long
dwY As Long
dwXSize As Long
dwYSize As Long
dwXCountChars As Long
dwYCountChars As Long
dwFillAttribute As Long
dwFlags As Long
wShowWindow As Integer
cbReserved2 As Integer
lpReserved2 As Byte
hStdInput As Long
hStdOutput As Long
hStdError As Long
End Type
Private Type SECURITY_ATTRIBUTES
nLength As Long
lpSecurityDescriptor As Long
bInheritHandle As Long
End Type
Private Enum enPriority_Class
NORMAL_PRIORITY_CLASS = &H20
IDLE_PRIORITY_CLASS = &H40
HIGH_PRIORITY_CLASS = &H80
End Enum
Private Declare Function CreateProcess Lib "kernel32" Alias "CreateProcessA" (ByVal lpApplicationName As String, ByVal lpCommandLine As String, lpProcessAttributes As SECURITY_ATTRIBUTES, lpThreadAttributes As SECURITY_ATTRIBUTES, ByVal bInheritHandles As Long, ByVal dwCreationFlags As Long, lpEnvironment As Any, ByVal lpCurrentDriectory As String, lpStartupInfo As STARTUPINFO, lpProcessInformation As PROCESS_INFORMATION) As Long
Private Declare Function WaitForSingleObject Lib "kernel32" (ByVal hHandle As Long, ByVal dwMilliseconds As Long) As Long
Private Function SuperShell(ByVal App As String, ByVal WorkDir As String, dwMilliseconds As Long, ByVal start_size As enSW, ByVal Priority_Class As enPriority_Class) As Boolean
Dim pclass As Long
Dim sinfo As STARTUPINFO
Dim pinfo As PROCESS_INFORMATION
'Not used, but needed
Dim sec1 As SECURITY_ATTRIBUTES
Dim sec2 As SECURITY_ATTRIBUTES
'Set the structure size
sec1.nLength = Len(sec1)
sec2.nLength = Len(sec2)
sinfo.cb = Len(sinfo)
'Set the flags
sinfo.dwFlags = STARTF_USESHOWWINDOW
'Set the window's startup position
sinfo.wShowWindow = start_size
'Set the priority class
pclass = Priority_Class
'Start the program
If CreateProcess(vbNullString, App, sec1, sec2, False, pclass, _
0&, WorkDir, sinfo, pinfo) Then
'Wait
WaitForSingleObject pinfo.hProcess, dwMilliseconds
SuperShell = True
Else
SuperShell = False
End If
End Function
Private Sub Form_Load()
'Set the dialog's title
CDBox.DialogTitle = "Choose an EXEC-File ..."
'Error when canceled
CDBox.CancelError = True
'Set the dialog's filter
CDBox.Filter = "EXEC-Files (*.exe)|*.exe|All files (*.*)|*.*"
'Show the 'Open File'-dialog
CDBox.ShowOpen
'Execute the program
SuperShell CDBox.FileName, Left$(CDBox.FileName, Len(CDBox.FileName) - Len(CDBox.FileTitle)), 0, SW_NORMAL, HIGH_PRIORITY_CLASS
End
End Sub

[jediknight]

感谢 ch21st(风尘鸟) 的回答,但是没有解决我的问题，我说详细一点吧：
Do While re <> 0
re = WaitForSingleObject(ProcHandle, 10000)
Loop
其中ProcHandle是个监视指定文件夹是否改变的进程，这个进程用FindFirstChangeNotification创建，这个进程在指定的文件夹得到改变之后返回
即我的目的是检测指定的文件夹是否发生变化，结果WaitForSingleObject将这个进程阻塞了，系统不能运行别的任何程序。我的理解是ProcHandle结束时WaitForSingleObject返回0，因此我判断re＝0时退出循环，程序实际运行当中发现re一直为-1，是不是我的理解有错误呀

[suntt]

呵呵，WaitForSingleObject用在进程和线程时它的作用是等待进程和线程的关闭
只要你的进程没有关闭WaitForSingleObject就会根据你设的时间等待下去

Return Values
If the function succeeds, the return value indicates the event that caused the function to return. This value can be one of the following.

Value Meaning
WAIT_ABANDONED The specified object is a mutex object that was not released by the thread that owned the mutex object before the owning thread terminated. Ownership of the mutex object is granted to the calling thread, and the mutex is set to nonsignaled.
WAIT_OBJECT_0 The state of the specified object is signaled.
WAIT_TIMEOUT The time-out interval elapsed, and the object's state is nonsignaled.
这是WaitForSingleObject的三种返回值

[jediknight]

调试不成功,郁闷