Creating Threads in C

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I am trying to implement a code which creates a thread. The thread writes into a file. If the thread has been created it returns 0 . The code here returns 0 but it does go into the fuction write() but does not writes in the file . Just to check it goes in the function i have put a printf() statement . Here is the code :-

#include<stdio.h>
#include<stdlib.h>
#include<pthread.h>

void *write(void *arg)
{

  printf("HI \n");
  FILE *fp;
  fp=fopen("file.txt","a");

  if(fp==NULL)
    {
      printf("error\n");
    }
else{
  fprintf(fp,"hello world");
  
 }
main()
{
  pthread_t thread;
  int tid;
  tid=pthread_create(&thread,NULL,write,NULL);
  printf("thread1 return %d \n",tid);
  exit(0);
}

Posted 24-Aug-13 17:23pm

Member 10200096

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Member 10200096 · Accepted Answer · 2013-08-24T19:38:00

Solution 1

The main need not to exit before the thread finishes so we have to add another function in main pthead_join () . Here is the edited code

C#

  main()
{
  thread_t thread;
  int tid;
  tid=pthread_create(&thread,NULL,write,NULL);
  printf("thread1 return %d \n",tid);
  pthread_join(thread, NULL);
  exit(0);
}

Posted 24-Aug-13 19:38pm

Member 10200096

Comments

pasztorpisti 25-Aug-13 6:45am

Every thread has an owner and every started thread must be joined by the owner at some point before the termination of the application. The termination of the application in case of native application happens either by calling an exit() like function or by returning from the main function with the main thread. In some (modern) languages the process doesn't disappear until the termination of any non-daemon threads.