WaitForSingleObject

Question

WaitForSingleObject这个函数看得一头雾水啊高人们讲解下啊

Answer 1

DWORD WaitForSingleObject( 
  HANDLE hHandle, 
  DWORD dwMilliseconds 
); 
WaitForSingleObject函数用来检测hHandle事件的信号状态，当函数的执行时间超过dwMilliseconds就返回，但如果参数dwMilliseconds为INFINITE时函数将直到相应时间事件变成有信号状态才返回，否则就一直等待下去，直到WaitForSingleObject有返回直才执行后面的代码。在这里举个例子：

Answer 2

给你一个示例代码
procedure TForm1.Button1Click(Sender: TObject);
  function WinExecAndWait32(FileName: string; Visibility: integer): Cardinal;
  var
    zAppName: array[0..512] of char;
    zCurDir: array[0..255] of char;
    WorkDir: string;
    StartupInfo: TStartupInfo;
    ProcessInfo: TProcessInformation;
  begin
    StrPCopy(zAppName, FileName);
    GetDir(0, WorkDir);
    StrPCopy(zCurDir, WorkDir);
    FillChar(StartupInfo, Sizeof(StartupInfo), #0);
    StartupInfo.cb := Sizeof(StartupInfo);
    StartupInfo.dwFlags := STARTF_USESHOWWINDOW;
    StartupInfo.wShowWindow := Visibility;
    if not CreateProcess(nil,
      zAppName,
      nil,
      nil,
      true,
      CREATE_NEW_CONSOLE or
      NORMAL_PRIORITY_CLASS,
      nil,
      nil,
      StartupInfo,
      ProcessInfo)
      then Result := INFINITE
    else
    begin
      WaitforSingleObject(ProcessInfo.hProcess, INFINITE);
      GetExitCodeProcess(ProcessInfo.hProcess, Result);
      CloseHandle(ProcessInfo.hProcess);
      CloseHandle(ProcessInfo.hThread);
    end;
  end;
begin
  WinExecAndWait32_v1('c:\1.exe',0);
end;

Answer 3

procedure TForm1.Button1Click(Sender: TObject);
  function WinExecAndWait32(FileName: string; Visibility: integer): Cardinal;
  var
    zAppName: array[0..512] of char;
    zCurDir: array[0..255] of char;
    WorkDir: string;
    StartupInfo: TStartupInfo;
    ProcessInfo: TProcessInformation;
  begin
    StrPCopy(zAppName, FileName);
    GetDir(0, WorkDir);
    StrPCopy(zCurDir, WorkDir);
    FillChar(StartupInfo, Sizeof(StartupInfo), #0);
    StartupInfo.cb := Sizeof(StartupInfo);
    StartupInfo.dwFlags := STARTF_USESHOWWINDOW;
    StartupInfo.wShowWindow := Visibility;
    if not CreateProcess(nil,
      zAppName,
      nil,
      nil,
      true,
      CREATE_NEW_CONSOLE or
      NORMAL_PRIORITY_CLASS,
      nil,
      nil,
      StartupInfo,
      ProcessInfo)
      then Result := INFINITE
    else
    begin
      WaitforSingleObject(ProcessInfo.hProcess, INFINITE);
      GetExitCodeProcess(ProcessInfo.hProcess, Result);
      CloseHandle(ProcessInfo.hProcess);
      CloseHandle(ProcessInfo.hThread);
    end;
  end;
begin
  WinExecAndWait32('c:\1.exe',0);
end;

Answer 4

WaitForSingleObject(   
    HANDLE  : hHandle,   
    DWORD  : dwMilliseconds   
);   
等到句柄为Handle的操作结束后才继续执行,另外时间不能超过DWORD,否则就继续执行下面的语句
一共2个参数
第一个是对象的句柄
比如说用CreateProcess创建一个进程,然后把进程的句柄叫给WaitForSingleObject就可以让程序等待到创建的进程结束之后再继续执行
第二个是超时时间,单位是毫秒,如果想一直等待它执行下去 这里就填INFINITE.