threadDeath1.cc

Go to the documentation of this file.

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

using namespace std;

//##########################################################
#define CHAR_EXAMPLE 
//##########################################################

void *myfunc(void *arg)
{
  //print whatever is in arg as a string 
  cout << *(string *)arg << endl;
  
#ifdef CHAR_EXAMPLE
  //demonstrate a char * return
  char *c = new char[256];
  memset(c, 0, 256);
  strcpy(c,"string from myfunc");
  cout << "myfunc returning:" << c <<endl;

  //pthread_exit((void *)c);

  return( (void *)c);

#else
  //demonstrate a string * return.
  string *s = new string("string from myfunc");
  cout << "myfunc returning:" << *s <<endl;

  /* DO NOT CALL pthread_exit from here */
  //pthread_exit((void *)s); 

  return( (void *)s);
#endif
}

void *func(void *arg)
{
  void *return_value = myfunc(arg);
  pthread_exit(return_value);
}

int main(int argc, char *argv[])
{
  //a thread id
  pthread_t tid;

  //return var from a pthread_exit()/pthread_join()
  void **ret;

  //a string to pass to myfunc()
  string arg("string from main");

  //##########################################################
  //##########################################################
  cout << "example 1:" << endl;
  //##########################################################

  //call a function tha calls the function
  pthread_create(&tid, (pthread_attr_t *)NULL, func, (void *)&arg);
  
  //join the thread
  pthread_join(tid, ret);

#ifdef CHAR_EXAMPLE
  //demonstrate a char * example
  char *pc = ((char *)(char *)*ret);
  cout << pc << endl;
  delete pc;
#else
  //demonstrate a string * example
  string *ps = ((string *)(string *)*ret);
  cout << *ps << endl;
  delete (string *)ps;
#endif

  //##########################################################
  //##########################################################
  /* Same type of example as above: this one just calls the function
  directly and uses more direct casting when accesing the return
  value from the function.
  */
  //##########################################################
  cout << "\n" << "example 2:" << endl;
  //##########################################################

  //creat thread 
  pthread_create(&tid, (pthread_attr_t *)NULL, myfunc, (void *)&arg);

  //join thread
  pthread_join(tid, ret);

#ifdef CHAR_EXAMPLE
  //access char through casts
  cout << ((char *)(char *)*ret) << endl;
  delete ((char *)(char *)*ret);
#else
  //access string through casts
  cout << *((string *)(string *)*ret) << endl;
  delete ((string *)(string *)*ret);
#endif

  return 0;
}