1. // 2.1.2.cpp : Defines the entry point for the console application.
2. //
3.  
4. #include "stdafx.h"
5. #include <iostream>
6. #include <stdlib.h>
7. #include <Windows.h>
8.  
9. #define nmax 10000
10.  
11. int sum;
12. int t[nmax];
13. #define threadCount 4
14. //Critical section
15. CRITICAL_SECTION cs;
16.  
17. DWORD WINAPI ThreadFunc(LPVOID lpdwParam) {
18.         int tid = (int)lpdwParam;
19.         int s = 0;
20.         int i;
21.         int dn = nmax / threadCount;
22.         int start = tid * dn;
23.         int stop = tid != threadCount - 1 ? (tid + 1)*dn : nmax;
24.         for (i = start; i<stop; i++) s += t[i];
25.         // Get into critical section
26.         EnterCriticalSection(&cs);
27.         sum += s;
28.         // Leave critical section
29.         LeaveCriticalSection(&cs);
30.         return 0;
31. }
32.  
33. int _tmain(int argc, _TCHAR* argv[])
34. {
35.         DWORD dwThreadId, dwThrdParam[threadCount];
36.         HANDLE ahThreads[threadCount];
37.  
38.         InitializeCriticalSection(&cs);
39.  
40.         int i, s = 0, z = 100;
41.         for (i = 0; i<nmax; i++) t[i] = rand() % z;
42.  
43.         //sequential
44.         s = 0;
45.         int time = GetTickCount();
46.         for (i = 0; i<nmax; i++) s += t[i];
47.         std::cout << "Sequential sum: " << s << std::endl;
48.         time = time - GetTickCount();
49.         std::cout << "Sequential sum time: " << s/10000 << " ticks of clock [*10000]" <<  std::endl;
50.         //parallel
51.         sum = 0;
52.         time = GetTickCount();
53.         for (i = 0; i<threadCount; i++)
54.         {
55.                 dwThrdParam[i] = i;
56.                 ahThreads[i] = CreateThread(NULL, 0, ThreadFunc, (LPVOID)dwThrdParam[i], 0, &dwThreadId);
57.         }
58.         for (i = 0; i<threadCount; i++)
59.         {
60.                 WaitForMultipleObjects(threadCount, ahThreads, true, INFINITE);
61.         }
62.         time = time - GetTickCount();
63.         std::cout << std::endl;
64.  
65.         std::cout << "Parallel sum: " << sum << std::endl;
66.         std::cout << "Parallel sum time: " << s / 10000 << " ticks of clock [*10000]" << std::endl;
67.         DeleteCriticalSection(&cs);
68.         std::cin.ignore(2);
69.         return 0;
70. }