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您现在的位置:首页> 开发|游戏程序|专业工具| > C++多线程(一)

C++多线程(一)

来源:IIEEG03-09-2011

WIN 多线程API

一 简单实例
比较简单的代码,创建10个线程,其中使第4个线程在一创建就挂起,等到其他的线程执行的差不多的时候再使第4个线程恢复执行。
#include
#include
#include

#define THREAD_NUM 10

DWORD WINAPI PrintThreads (LPVOID);

int main ()
{
    HANDLE hThread[THREAD_NUM];
    DWORD dwThreadID[THREAD_NUM];

    for (int i=0; i     {
        int isStartImmediate = 0;
        if(3 == i)
            isStartImmediate = CREATE_SUSPENDED;
        hThread[i]=CreateThread(NULL,                // security attributes that should be applied to the new thread,
                                                                                 // this is for NT. Use NULL to get the default security attributes. Use NULL for win95
                                0,                                            // default size of 1MB can be passed by passing zero.
                                PrintThreads,                     // function name:address of the function where the new thread starts.
                                (LPVOID)i,                         // parameter(void pointer): pointer to the 32 bit parameter that will be passed into the thread
                                isStartImmediate,             // flags to control the creation of the thread. Passing zero starts the thread immediately.
                                                                           // Passing CREATE_SUSPENDED suspends the thread until the ResumeThread( ) function is called.
                                &dwThreadID[i]            // pointer to a 32-bit variable that receives the thread identifier.
                                );
        if (hThread[i])
        {
            printf ("Thread launched successfully\n");               
        }        
    }
    printf("Start sleep 100, and let other thread excute\n");
    Sleep (100);   

    printf("Start sleep 100, and thread 3 excute\n");
    ResumeThread(hThread[3]);
   
    Sleep(100);

    for(int i = 0; i     {
        if (hThread[i])
        {           
            CloseHandle(hThread[i]);    // You need to use this to release kernel objects when you are done using them.
                                        // If a process exits without closing the thread handle,
                                        // the operating system drops the reference counts for those objects.
                                        // But if a process frequently creates threads without closing the handles,
                                        // there could be hundreds of thread kernel objects lying around and these resource leaks can have a big hit on performance.
        }
    }
    return (0);
}

//function PrintThreads
DWORD WINAPI PrintThreads (LPVOID num)
{
    for (int i=0; i<10; i++)
        printf ("Thread Number is %d%d%d\n", num,num,num);
    return 0;
}

二 其他基本API的说明
CreateThread() 调用成功返回句柄和一个id。
CloseHandle()  关闭一个打开的对象句柄,该对象句柄可以是线程句柄,也可以是进程、信号量等其他内核对象的句柄.

SuspendThread(HANDLE) 允许开发人员将HANDLE指定的线程挂起,如果要挂起的线程占有共享资源,则可能导致死锁。
ResumeThread(HANDLE)  恢复指定的线程。

TerminateThread() 立即终止线程的工作,不做任何清理工作。
ExitThread() 线程函数返回时回调用次函数,所以一般我们不去显示的调用。

ExitThread是推荐使用的结束一个线程的方法,当调用该函数时,当前线程的栈被释放,然后线程终止,相对于TerminateThread函数来说,这样做能够更好地完成附加在该线程上的DLL的清除工作. 但是ExitThread()会导致线程在清处构造器/自动变量之前就终止,所以我们最好不要显示的调用ExitThread()。