pthread_cancel.c

#include <errno.h>                                                              
#include <pthread.h>                                                            
#include <stdio.h>                                                              
#include <string.h>                                                             
#include <unistd.h>
#include <stdlib.h> // exit()                                                          
                                                                                
int  thstatus;                                                                  
                                                                                
void * thread(void *arg)                                                        
{                                                                               
  puts("thread has started. now sleeping");                                      
  while (1)                                                                      
    sleep(1);
    // unsigned int sleep(unsigned int seconds); - sleep for a specified number of seconds                                                                  
}                                                                               
                                                                                
int main(int argc, char *argv[])                                                    
{                                                                               
  pthread_t      thid;                                                           
  void           *status;                                                        
                                                                                 
  if ( pthread_create(&thid, NULL, thread, NULL) != 0) {                         
    perror("pthread_create failed");
    // perror - print a system error message                                    
    exit(2);                                                                     
  }                                                                              
                                                                                 
  if ( pthread_cancel(thid) == -1 ) {                                            
    perror("pthread_cancel failed");                                             
    exit(3);                                                                     
  }                                                                              
                                                                                 
  if ( pthread_join(thid, &status)== -1 ) { 
    // int pthread_join(pthread_t thread, void **retval);
    // The pthread_join() function waits for the thread specified by thread to terminate.
    // If retval is not NULL, then pthread_join() copies the exit status of the target thread
    // into the location pointed to by retval.                                    
    perror("pthread_join failed");                                               
    exit(4);                                                                     
  }                                                                              
                                                                                 
  if ( status == PTHREAD_CANCELED )                                                     
    puts("thread was cancelled");                                                
  else                                                                           
    puts("thread was not cancelled");                                            
                                                                                 
  exit(0);                                                                       
}