[总结] C++ 知识点 《四》多线程相关

#include <stdio.h>
#include <stdlib.h>
#include <vector>
#include <iostream>
#include <memory>
#include <thread>
#include <mutex>
#define MAX_SIZE 200*1024
#define MAX_THREAD_COUNT 10
int main() {
  FILE* pFile = fopen("D:\\workspace\\vs2015\\Project1\\Debug\\data.txt","rb");
  if (!pFile) {
    printf("file open error \n");
    return -1;
  }
  char szBuff[MAX_SIZE] = { 0 };
  int i = 0;
  while (!feof(pFile)) {
    fread(&szBuff[i * 1024], 1, 1024, pFile);
    i++;
  }
  fclose(pFile);    
  char szDoubleValue[8] = {0};
  int nDoubleValueIndex = 0;
  std::vector<double> vectDoubleList;
  for (size_t i = 0; i < strlen(szBuff); i++)
  {
    if (szBuff[i] == '\r') {
      float fValue = atof(szDoubleValue);
      vectDoubleList.push_back(fValue);
      //printf("%f\n", fValue);
      continue;
    }
    if (szBuff[i] == '\n') {
      nDoubleValueIndex = 0;
      memset(szDoubleValue, 0, 8);
      continue;
    }
    szDoubleValue[nDoubleValueIndex] = szBuff[i];
    nDoubleValueIndex++;
  }
  if (vectDoubleList.size() <= 0) {
    printf("vectDoubleList empty \n");
    return -1;
  }
  std::unique_ptr<std::thread> thThreadPtrList[MAX_THREAD_COUNT - 1];
  volatile int nHasProIndex = 0;
  double dTotalValue = 0;
  int size = vectDoubleList.size();
  std::mutex lock;
  long lStartTime = clock();
  for (size_t i = 0; i < MAX_THREAD_COUNT - 1; i++)
  {
    thThreadPtrList[i] = std::unique_ptr<std::thread>(
      new std::thread([&]() {
        while(1)
        {
          std::lock_guard<std::mutex> locker(lock);
          if (nHasProIndex != size) {
            dTotalValue += vectDoubleList[nHasProIndex];
            nHasProIndex++;
          }
          else {
            break;
          }
        }
      })
    );
  }
  while (1)
  {
    std::lock_guard<std::mutex> locker(lock);
    if (nHasProIndex != size) {
      dTotalValue += vectDoubleList[nHasProIndex];
      nHasProIndex++;
    }
    else {
      break;
    }
  }
  long lEndTime = clock();
  double dAvarageValue = dTotalValue / vectDoubleList.size();
  printf("Total Count:%d \nMedium Value:%f \nAvarage Value:%f \n", vectDoubleList.size(),vectDoubleList[vectDoubleList.size()/2], dAvarageValue);
  printf("Total Time:%d \n", lEndTime - lStartTime);
  for (size_t i = 0; i < MAX_THREAD_COUNT -1; i++)
  {
    thThreadPtrList[i]->join();
  }
  system("pause");
  return 0;
}