深入浅出MFC中的多线程问题

[zhangxile]

#include<WINDOWS.H>
#include<PROCESS.H>
unsigned _stdcall myfunc(void* p);
#include<iostream.h>
void main()
{
unsigned long thd;
unsigned tid;

thd= _beginthreadex(NULL,
0,
myfunc,
0,
0,
&tid);
if(thd!=NULL)
{
CloseHandle(thd);
}
}
unsigned _stdcall myfunc(void* p)
{
cout<<"Inside processing"<<endl;
return 0;

}



--------------------Configuration: test - Win32 Debug--------------------
Compiling...
test.cpp
D:\Program Files\Microsoft Visual Studio\MyProjects\test001\test.cpp(18) : error C2664: 'CloseHandle' : cannot convert parameter 1 from 'unsigned long' to 'void *'
Conversion from integral type to pointer type requires reinterpret_cast, C-style cast or function-style cast
Error executing cl.exe.

test.exe - 1 error(s), 0 warning(s)

[arong1234]

这里是各类型问题，不知道为什么这个api用long做返回类型
你强制转换成HANDLE即可

[zhangxile]

我试过了,结果出现了3个error啊~~

[zhangxile]

怎么解决啊?

[Supper_Jerry]

CloseHandle不能这么使用的。查一下beginthreadex使用方法吧。

[独孤过儿]

楼主好像弄错函数的返回值了吧...

uintptr_t _beginthread( 
   void( *start_address )( void * ),
   unsigned stack_size,
   void *arglist 
);
uintptr_t _beginthreadex( 
   void *security,
   unsigned stack_size,
   unsigned ( *start_address )( void * ),
   void *arglist,
   unsigned initflag,
   unsigned *thrdaddr 
);

[Supper_Jerry]

HANDLE hD= (HANDLE )_beginthreadex(NULL,
0,
myfunc,
0,
0,
&tid); 试一下。

[珍惜生命远离CPP]

thd 是HANDLE类型的,_beginthread的返回值需要强制转化成HANDLE类型

[独孤过儿]

再给你贴个例子：

// crt_begthrdex.cpp
// compile with: /MT
#include <windows.h>
#include <stdio.h>
#include <process.h>

unsigned Counter; 
unsigned __stdcall SecondThreadFunc( void* pArguments )
{
    printf( "In second thread...\n" );

    while ( Counter < 1000000 )
        Counter++;

    _endthreadex( 0 );
    return 0;
} 

int main()
{ 
    HANDLE hThread;
    unsigned threadID;

    printf( "Creating second thread...\n" );

    // Create the second thread.
    hThread = (HANDLE)_beginthreadex( NULL, 0, &SecondThreadFunc, NULL, 0, &threadID );

    // Wait until second thread terminates. If you comment out the line
    // below, Counter will not be correct because the thread has not
    // terminated, and Counter most likely has not been incremented to
    // 1000000 yet.
    WaitForSingleObject( hThread, INFINITE );
    printf( "Counter should be 1000000; it is-> %d\n", Counter );
    // Destroy the thread object.
    CloseHandle( hThread );
}

输出：
Creating second thread...
In second thread...
Counter should be 1000000; it is-> 1000000

[zhangxile]

#include<WINDOWS.H>
#include<PROCESS.H>
unsigned _stdcall myfunc(void* p);
#include<iostream.h>
void main()
{
unsigned long thd;
unsigned tid;

thd= _beginthreadex(NULL,
0,
myfunc,
0,
0,
&tid);
if(thd!=NULL)
{
CloseHandle((HANDLE)thd);
}
}
unsigned _stdcall myfunc(void* p)
{
cout<<"Inside processing"<<endl;
return 0;

}



--------------------Configuration: test - Win32 Debug--------------------
Compiling...
test.cpp
Linking...
dd.obj : error LNK2005: _main already defined in test.obj
libcimtd.lib(iostrini.obj) : error LNK2001: unresolved external symbol "void * __cdecl operator new(unsigned int,int,char const *,int)" (??2@YAPAXIHPBDH@Z)
libcimtd.lib(streamb.obj) : error LNK2001: unresolved external symbol "void * __cdecl operator new(unsigned int,int,char const *,int)" (??2@YAPAXIHPBDH@Z)
Debug/test.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.

test.exe - 4 error(s), 0 warning(s)