几个简单程序加深你对多线程和信号量的理解

#include <windows.h>
#include <iostream.h>

HANDLE g_hSemp1 = NULL;
HANDLE g_hSemp2 = NULL;

DWORD WINAPI ThreadProc(LPVOID pVoid);

int main()
{
	cout << "main thread" << endl;
	g_hSemp1 = CreateSemaphore(NULL, 1, 10, NULL);
	g_hSemp2 = CreateSemaphore(NULL, 1, 10, NULL);

	HANDLE hThread = CreateThread(NULL, 0, ThreadProc, NULL, 0, NULL);
	
	CloseHandle(hThread);
	CloseHandle(g_hSemp1);
	CloseHandle(g_hSemp2);

	return 0;
}

DWORD WINAPI ThreadProc(LPVOID pVoid)
{
	WaitForSingleObject(g_hSemp1, INFINITE);
	cout << "thread" << endl;
	ReleaseSemaphore(g_hSemp1, 1, NULL);

	return 0;
}

     结果：

main thread

 

#include <windows.h>
#include <iostream.h>

HANDLE g_hSemp1 = NULL;
HANDLE g_hSemp2 = NULL;

DWORD WINAPI ThreadProc(LPVOID pVoid);

int main()
{
	cout << "main thread" << endl;
	g_hSemp1 = CreateSemaphore(NULL, 1, 10, NULL);
	g_hSemp2 = CreateSemaphore(NULL, 1, 10, NULL);

	HANDLE hThread = CreateThread(NULL, 0, ThreadProc, NULL, 0, NULL);
	Sleep(1000);
	
	CloseHandle(hThread);
	CloseHandle(g_hSemp1);
	CloseHandle(g_hSemp2);

	return 0;
}

DWORD WINAPI ThreadProc(LPVOID pVoid)
{
	WaitForSingleObject(g_hSemp1, INFINITE);
	cout << "thread" << endl;
	ReleaseSemaphore(g_hSemp1, 1, NULL);

	return 0;
}

     结果：

main thread

thread

 

#include <windows.h>
#include <iostream.h>

HANDLE g_hSemp1 = NULL;
HANDLE g_hSemp2 = NULL;

DWORD WINAPI ThreadProc(LPVOID pVoid);

int main()
{
	cout << "main thread" << endl;
	g_hSemp1 = CreateSemaphore(NULL, 0, 10, NULL);
	g_hSemp2 = CreateSemaphore(NULL, 1, 10, NULL);

	HANDLE hThread = CreateThread(NULL, 0, ThreadProc, NULL, 0, NULL);
	Sleep(1000);
	
	CloseHandle(hThread);
	CloseHandle(g_hSemp1);
	CloseHandle(g_hSemp2);

	return 0;
}

DWORD WINAPI ThreadProc(LPVOID pVoid)
{
	WaitForSingleObject(g_hSemp1, INFINITE);
	cout << "thread" << endl;
	ReleaseSemaphore(g_hSemp1, 1, NULL);

	return 0;
}

     结果：

main thread

 

#include <windows.h>
#include <iostream.h>

HANDLE g_hSemp1 = NULL;
HANDLE g_hSemp2 = NULL;

DWORD WINAPI ThreadProc(LPVOID pVoid);

int main()
{
	cout << "main thread" << endl;
	g_hSemp1 = CreateSemaphore(NULL, 1, 10, NULL);
	g_hSemp2 = CreateSemaphore(NULL, 1, 10, NULL);

	HANDLE hThread = CreateThread(NULL, 0, ThreadProc, NULL, 0, NULL);
	Sleep(1000);
	
	CloseHandle(hThread);
	CloseHandle(g_hSemp1);
	CloseHandle(g_hSemp2);

	return 0;
}

DWORD WINAPI ThreadProc(LPVOID pVoid)
{
	WaitForSingleObject(g_hSemp1, INFINITE);
	WaitForSingleObject(g_hSemp2, INFINITE);
	cout << "thread" << endl;
	ReleaseSemaphore(g_hSemp1, 1, NULL);
	ReleaseSemaphore(g_hSemp2, 1, NULL);

	return 0;
}

     结果：

main thread

thread

 

#include <windows.h>
#include <iostream.h>

HANDLE g_hSemp1 = NULL;
HANDLE g_hSemp2 = NULL;

DWORD WINAPI ThreadProc(LPVOID pVoid);

int main()
{
	cout << "main thread" << endl;
	g_hSemp1 = CreateSemaphore(NULL, 1, 10, NULL);
	g_hSemp2 = CreateSemaphore(NULL, 0, 10, NULL);

	HANDLE hThread = CreateThread(NULL, 0, ThreadProc, NULL, 0, NULL);
	Sleep(1000);
	
	CloseHandle(hThread);
	CloseHandle(g_hSemp1);
	CloseHandle(g_hSemp2);

	return 0;
}

DWORD WINAPI ThreadProc(LPVOID pVoid)
{
	WaitForSingleObject(g_hSemp1, INFINITE);
	WaitForSingleObject(g_hSemp2, INFINITE);
	cout << "thread" << endl;
	ReleaseSemaphore(g_hSemp1, 1, NULL);
	ReleaseSemaphore(g_hSemp2, 1, NULL);

	return 0;
}

     结果：

main thread

 

#include <windows.h>
#include <iostream.h>

HANDLE g_hSemp1 = NULL;
HANDLE g_hSemp2 = NULL;

DWORD WINAPI ThreadProc(LPVOID pVoid);

int main()
{
	cout << "main thread" << endl;
	g_hSemp1 = CreateSemaphore(NULL, 1, 10, NULL);
	g_hSemp2 = CreateSemaphore(NULL, 1, 10, NULL);

	HANDLE hThread = CreateThread(NULL, 0, ThreadProc, NULL, 0, NULL);
	Sleep(1000);
	
	CloseHandle(hThread);
	CloseHandle(g_hSemp1);
	CloseHandle(g_hSemp2);

	return 0;
}

DWORD WINAPI ThreadProc(LPVOID pVoid)
{
	WaitForSingleObject(g_hSemp1, INFINITE);
	WaitForSingleObject(g_hSemp1, INFINITE);
	cout << "thread" << endl;
	ReleaseSemaphore(g_hSemp1, 1, NULL);
	ReleaseSemaphore(g_hSemp2, 1, NULL);

	return 0;
}

     结果：

main thread

 

#include <windows.h>
#include <iostream.h>

HANDLE g_hSemp1 = NULL;
HANDLE g_hSemp2 = NULL;

DWORD WINAPI ThreadProc(LPVOID pVoid);

int main()
{
	cout << "main thread" << endl;
	g_hSemp1 = CreateSemaphore(NULL, 1, 10, NULL);
	g_hSemp2 = CreateSemaphore(NULL, 0, 10, NULL);

	HANDLE hThread = CreateThread(NULL, 0, ThreadProc, NULL, 0, NULL);
	Sleep(1000);
	
	CloseHandle(hThread);
	CloseHandle(g_hSemp1);
	CloseHandle(g_hSemp2);

	return 0;
}

DWORD WINAPI ThreadProc(LPVOID pVoid)
{
	WaitForSingleObject(g_hSemp1, INFINITE);
	WaitForSingleObject(g_hSemp2, INFINITE);
	ReleaseSemaphore(g_hSemp2, 1, NULL);
	cout << "thread" << endl;

	return 0;
}

     结果：

main thread

 

#include <windows.h>
#include <iostream.h>

HANDLE g_hSemp1 = NULL;
HANDLE g_hSemp2 = NULL;

DWORD WINAPI ThreadProc(LPVOID pVoid);

int main()
{
	cout << "main thread" << endl;
	g_hSemp1 = CreateSemaphore(NULL, 1, 10, NULL);
	g_hSemp2 = CreateSemaphore(NULL, 0, 10, NULL);

	HANDLE hThread = CreateThread(NULL, 0, ThreadProc, NULL, 0, NULL);
	Sleep(1000);
	
	CloseHandle(hThread);
	CloseHandle(g_hSemp1);
	CloseHandle(g_hSemp2);

	return 0;
}

DWORD WINAPI ThreadProc(LPVOID pVoid)
{
	WaitForSingleObject(g_hSemp1, INFINITE);
	ReleaseSemaphore(g_hSemp2, 1, NULL);
	WaitForSingleObject(g_hSemp2, INFINITE);
	cout << "thread" << endl;

	return 0;
}

     结果：

main thread

thread

 

     好了，如果你愿意，你可以自己去变换程序，然后运行，并分析结果，相信对你理解多线程和信号量是有帮助的。