Question

如何将void指针矢量数组转换为矢量数组？

vector<string>* vArray = new vector<string[numThreads];

p_thread_create(&my_thread[1], NULL, &function, (void)* vArray[1]);

void* function (vector<string> vArray[])
{
 //?? casting?
}

当作为参数传递时（void）* vArray [1]它表示无效的演员...... 如果函数有2个参数，那么pthread可以创建更多参数，例如2吗？感谢

这是我的完整代码

#include <iostream>
#include <iomanip>
#include <iterator>
#include <sstream>
#include <fstream>
#include <string>
#include <vector>
#include <pthread.h>
#include <queue>

using namespace std;

int array[5] = { 0, 0, 0, 0, 0 };

void* readData(void* arg)
{

  string fileName = "Wisconsin.txt";
  cout << "HERE!"<< endl;
  ifstream cities(fileName.c_str());
  string line;
  while(!cities.eof()){
    getline(cities, line);
    if(line != "") {
      int commaPos = line.find(',');
      int popul = atoi(line.substr(commaPos + 2).c_str());
      int x = popul;
      if (x >= 1 && x <= 999)
        {
          array[0]++;
        } else
        if (x >= 1000 && x <= 9999)
          {
            array[1]++;
          } else
          if (x >= 10000 && x <= 99999)
            {
              array[2]++;
            } else
            if (x >= 100000 && x <= 999999)
              {
                array[3]++;
              } else
              if (x >= 1000000)
                {
                  array[4]++;
                }

    } // end of IF 
  }  // end of while 
}

int main()
{
  int numThreads;
  ifstream ifs("states.txt");
  std::string str((std::istreambuf_iterator<char>(ifs)),
                  std::istreambuf_iterator<char>());
  stringstream ss(str);
  int fileCount = 0;
  string fileName;
  while (ss >> fileName)
    {
      fileCount++;
    }
  cout << fileCount;

  string* filesArr = new string[fileCount];
  ss.clear();
  ss.seekg(0, std::ios::beg);
  for (int i = 0; i < fileCount; i++)
    {
      ss >> filesArr[i];
    }   

  cout << "Enter number of threads: ";
  cin >> numThreads;

  vector<string>* vArray = new vector<string>[numThreads];
  for (int i = 0; i < fileCount; i++)
    {
      vArray[i % numThreads].insert(vArray[i % numThreads].begin(), filesArr[i]);
    }

  //queue<string>* queueArr = new queue<string>[numThreads];
  //for (int i = 0; i < fileCount; i++)
    //  queueArr[i % numThreads].push(filesArr[i]);

  for(int i = 0; i < numThreads; i ++)
    {
      cout << endl;
      cout << "FOR THREAD " << i + 1 << ":" << endl;
      for (std::vector<string>::iterator it = vArray[i].begin(); it != vArray[i].end(); it++)
        {
          cout << *it << endl;

        }

    }


  pthread_t my_thread[numThreads];
  int ret = pthread_create(&my_thread[1], NULL, &readData, (void*)(vArray+1));
  /////////////////////////////////////////////////////////////////////////
  /////////////////////////////////////////////////////////////////////////
  /////////////////////////////////////////////////////////////////////////
  ///////////// ERROR HERE!
  pthread_join(my_thread[1], ret);
  // for (int id = 0; id < numThreads; id++)
  //    {
  //}

  pthread_join(my_thread[1]);
  cout << endl;

  printf("%-20s", "1-999:");
  cout << array[0] << endl;

  printf("%-20s", "1,000 - 9,999:");
  cout << array[1] << endl;

  printf("%-20s", "10,000-99,999:");
  cout << (array[2]) << endl;

  printf("%-20s", "100,000-999,999:");
  cout << (array[3]) << endl;

  printf("%-20s", "1,000,000+:");
  cout << (array[4]) << endl;

  //int pos;
  //string token;
  //while ((pos = s.find(delimiter))

  cin.get();

  return 0;
}

pthread join现在似乎没有工作..编译它返回我：函数'int pthread_join（pthread_t，void **）的参数太少

Answer 1

清理完代码后：

#include <iostream>
#include <vector>
using namespace std;

const int numThreads = 10;

void * thread_body (void * param)
{
    // retrieve parameter
    string& prm = *(string *)param;

    // use it
    cout << prm << endl;

    return NULL;
}

int main() {
    vector<string   >threadPrm(numThreads);
    vector<pthread_t>threadId (numThreads);

    threadPrm[1] = "Hello";
    pthread_create(&threadId[1], NULL, thread_body, &threadPrm[1]);
    pthread_join (threadId[1], NULL);

    return 0;
}

你似乎对

感到满意

载体
指针和参考
变量命名

此外，尝试使用静态强制转换关闭编译器是生成愚蠢代码的可靠方法关键是通常使代码运行，而不是不惜一切代价编译它。

最后，您可以通过reading the manual

回答您自己关于posix线程可以采用的参数数量的问题。

pthread_create将动态矢量数组传递给参数

1 个答案: