Thread: creating POSIX threads in UNIX

  1. #1
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    creating POSIX threads in UNIX

    Code:
    #include <pthread.h>
    #include <iostream>
    using namespace std;
    
    
    void myfunc()
    {
            cout<<"hello"<<endl;
    }
    int main()
    {
    
            pthread_t *thread1;
            thread1 = (pthread_t*)calloc(1,sizeof(pthread_t));
            pthread_create(thread1,NULL,(void *)(&myfunc),NULL);
            return 0;
    }
    when i try to run get an error saying: main.cpp:15: error: invalid conversion from `void*' to `void*(*)(void*). This is just to test to see that i can create a thread to simualte a producer/consumer threads.

  2. #2
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    Give this a try:

    Code:
    #include <pthread.h>
    #include <iostream>
    using namespace std;
    
    
    void* myfunc(void *param)
    {
            cout<<"hello"<<endl;
    }
    int main()
    {
    
            pthread_t *thread1;
            thread1 = (pthread_t*)calloc(1,sizeof(pthread_t));
            pthread_create(thread1,NULL,myfunc,NULL);
            return 0;
    }

  3. #3
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    Code:
      #include <pthread.h>
      #include <iostream>
      using namespace std;
      
      void *myfunc(void *data)
      {
      cout<<"hello"<<endl;
      }
      int main()
      {
      
              pthread_t *thread1;
              thread1 = (pthread_t*)calloc(1,sizeof(pthread_t));
              pthread_create(thread1, NULL, myfunc, NULL);
              return 0;
      }
    (edit) next time I'll leave the colors away to be faster°°

  4. #4
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    when i execute that code i get a: Segmentation fault (core dumped)

  5. #5
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    You get a seg fault because your main thread ends before your spawned thread.
    Give this a try:

    Code:
    void* myfunc(void *param)
    {
       cout<<"hello"<<endl;
       return 0;
    }
    int main()
    {
       pthread_t thread1;
       pthread_create(&thread1,NULL,myfunc,NULL);
       pthread_join(thread1,0);
       return 0;
    }

  6. #6
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    The pthread_join() function tells the main thread to wait for the spawned thread to end before continuing.

  7. #7
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    i tried doing that, now it gives me a /var/tmp//ccjC6FRg.o(.text+0x62): In function `main':
    : undefined reference to `pthread_join'

    I have #include<pthread.h>

  8. #8
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    You have to link to the pthread library. Pass -lpthread to your linker.

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