Thread: Pthreads...

I started using pthreads recently and tried to execute the following code in quad core processor..

Code:

#include <pthread.h>
#include<iostream>
#include <vector>

using namespace std;

vector<int> num;

void *threadfunc(void *arg)
{
  int *input=(int*) arg;

  for(int i=1;i<5;i++)
    {
      num.push_back((*input)*i);
    }

  return NULL;
}

int main()
{
  pthread_t threadID[4];
  void *exit_status;
 
  for(int i=0;i<4;i++)
    {
      pthread_create(&threadID[i],NULL,threadfunc,&i);
    }
  for(int i=0;i<4;i++)
    {
      pthread_join(threadID[i],&exit_status);
    }
  for(int i=0;i<num.size();i++)
    {
      cout<<num[i]<<endl;
    }

  return 0;
}

Here is another version of same code

Code:

#include <pthread.h>
#include<iostream>
#include <vector>

using namespace std;

vector<int> num;
vector<int> contain;

void *threadfunc(void *arg)
{
  num.clear();
  int *input=(int*) arg;

  for(int i=1;i<5;i++)
    {
      num.push_back((*input)*i);
    }

  //cout<<"K"<<endl;
  return &num;
}

int main()
{
  pthread_t threadID[4];
  void *exit_status;
  vector<int> *hold;
  int count=0;
  vector<int>:: iterator it;
  void *threadfunc(void *arg);

  it=contain.begin();

  count=10;
 
  for(int i=0;i<4;i++)
    {
      pthread_create(&threadID[i],NULL,threadfunc,&i);
    }
  for(int i=0;i<4;i++)
    {
      pthread_join(threadID[i],&exit_status);
      hold=(vector<int> *)exit_status;

      contain.insert(it,(*hold).begin(),(*hold).end());
      (*hold).clear();
      exit_status=NULL;

    }

  for(int i=0;i<contain.size();i++)
    {
      cout<<contain[i]<<endl;
    }

  return 0;
}

It compiles fine and gives an output in a single processor but in quad core, I get

Segmentation Fault (core dumped)

Kindly help....