pi.rar_PI_Visual studio linux_pi c++_多线程求pi

#include<stdio.h> #include<process.h> #include<windows.h> #include<time.h> #define NUM_THREAD 4 #define MAX 10000000 double sum=0,dstep=(double)1/MAX; unsigned __stdcall ThreadFunc(void* args); CRITICAL_SECTION lpCS; int main(int argc,char* argv[]) { HANDLE thread[NUM_THREAD]; unsigned int threadID[NUM_THREAD]; int i; clock_t start,finish; InitializeCriticalSection(&lpCS); start=clock(); for(i=0;i<NUM_THREAD;i++) { thread[i]=(HANDLE)_beginthreadex(NULL,0,&ThreadFunc,NULL,0,&threadID[i]); } WaitForMultipleObjects(NUM_THREAD,thread,TRUE,INFINITE); DeleteCriticalSection(&lpCS); finish=clock(); printf("the pi is %12.10f\n",sum); printf("the time to calculate pi was %lf millionseconds\n",(double)(finish-start)); system("pause"); return 0; } unsigned __stdcall ThreadFunc(void* args) { double x=0,partSum=0; long int i; for(i=0;i<MAX;i+=NUM_THREAD) { x=(i+0.5)*dstep; partSum+=4/(1+x*x); } partSum=partSum*dstep; EnterCriticalSection(&lpCS); sum=sum+partSum; LeaveCriticalSection(&lpCS); _endthreadex(0); return 0; }