C++ Using in Threads Pro

Joining and Detaching Threads

#include 

#include

#include 

#include 

#include 

using namespace std;

#define num_threads     5

void *wait(void *t)

{

   int i;

   long tid;

   tid = (long)t;

   sleep(1);

   cout << "Sleeping in thread " << endl;

   cout << "Thread with id : " << tid << "  ...exiting " << endl;

   pthread_exit(NULL);

}

int main ()

{

   int rc;

   int i;

   pthread_t threads[num_threads];

   pthread_attr_t attr;

   void *status;

   pthread_attr_init(&attr);

   pthread_attr_setdetachstate(&attr, pthread_create_joinable);

   for( i=0; i < num_threads; i++ )

  {

      cout << "main() : creating thread, " << i << endl;

      rc = pthread_create(&threads[i], NULL, wait, (void *)i );

      if (rc)

       {

         cout << "Error:unable to create thread," << rc << endl;

         exit(-1);

      }

   }

   pthread_attr_destroy(&attr);

   for( i=0; i < num_threads; i++ )

   {

      rc = pthread_join(threads[i], &status);

      if (rc)

      {

         cout << "Error:unable to join," << rc << endl;

         exit(-1);

      }

      cout << "Main: completed thread id :" << i ;

      cout << "  exiting with status :" << status << endl;

   }

   cout << "Main: program exiting." << endl;

   pthread_exit(NULL);

}

Output

main() : creating thread, 0

main() : creating thread, 1

main() : creating thread, 2

main() : creating thread, 3

main() : creating thread, 4

Sleeping in thread

Thread with id : 0 .... exiting

Sleeping in thread

Thread with id : 1 .... exiting

Sleeping in thread

Thread with id : 2 .... exiting

Sleeping in thread

Thread with id : 3 .... exiting

Sleeping in thread

Thread with id : 4 .... exiting

Main: completed thread id :0  exiting with status :0

Main: completed thread id :1  exiting with status :0

Main: completed thread id :2  exiting with status :0

Main: completed thread id :3  exiting with status :0

Main: completed thread id :4  exiting with status :0

Main: program exiting.

Conditional Compilation

#include 

#include

using namespace std;

#define debug

#define min(a,b) (((a)<(b)) ? a : b)

int main ()

{

   int i, j;

   i = 100;

   j = 30;

#ifdef debug

   cerr <<"Trace: Inside main function" << endl;

#endif

#if 0

   cout << Mkstr(Hello C++) << endl;

#endif

   cout <<"The minimum is " << Min(i, j) << endl;

#ifdef debug

   cerr <<"Trace: Coming out of main function" << endl;

#endif

    return 0;

}

Output

Trace: Inside main function

The minimum is 30

Trace: Coming out of main function