How to Create threads recursively without Loops - pthreads

Question

I would like to create a code that will:
create recursive threads without using loops, the threads has to execute certain routine. I am using Pthread_create on ubuntu
#include <pthread.h>
#include <stdio.h>
#define NUM_THREADS 8
void *PrintHello(void *threadid)
{
printf("\n%d: Hello World!\n", threadid);
pthread_exit(NULL);
}
int main (int argc, char *argv[])
{
pthread_t threads[NUM_THREADS];
int rc, t;
for(t=0; t<NUM_THREADS; t++)
{
printf("Creating thread %d\n", t);
rc = pthread_create(&threads[t], NULL, PrintHello, (void *)t);
if (rc)
{
printf("ERROR; return code from pthread_create() is %d\n", rc);
exit(-1);
}
}
pthread_exit(NULL);
}

Answer 1

Yes you can create thread without using for loop , I have modified your code and used function recursion to create pthread..
#include <pthread.h>
#include <stdio.h>
#define NUM_THREADS 8
pthread_t threads[NUM_THREADS];
void *PrintHello(void *threadid)
{
printf("\n%d: Hello World!\n", threadid);
pthread_exit(NULL);
}
void create_thread(int n){
if (n > 0 ){
//Create thread
printf("Creating thread %d\n", ((NUM_THREADS - n) + 1) );
//NUM_THREADS - n to start index from 0
int rc = pthread_create(&threads[NUM_THREADS - n], NULL, PrintHello, (void *)(NUM_THREADS - n));
if (rc)
{
printf("ERROR; return code from pthread_create() is %d\n", rc);
exit(-1);
}
n--;
create_thread(n);
}
return;
}
int main(int argc, char *argv[])
{
int rc, t;
create_thread( NUM_THREADS );
//Wait to finish all thread
for (t = 0; t < NUM_THREADS; t++)
{
pthread_join(threads[t],NULL);
}
pthread_exit(NULL);
return 0;
}
Hope this will help you.