How to switch among two threads alternatively ??

Suppose I wish to prints the characters of a string one by one alternatively using only two threads ......
How should I proceed ??

Should I use fork() to divide create a copy of the thread and then pass a new argument to it ???

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

void *read_char(void *ptr) {
   char c;
   c = (char) ptr;

   printf("%c", c);
}

int main(void) {
   pthread_t Thread1, Thread2;
   char *str = "This is a string!";
   int len, i;
   len = strlen(str);
   
   for (i=0; i<len; ++i) {
      pthread_create (&thr, NULL, read_char, (void*) str[i]);    
   }
.
.
.
.

I wish the output to be something as ..

Thread 1: T
Thread 2: h
Thread 1: i
Thread 2: s
Thread 1: 
Thread 2: i
.
.
.

Please help !

You may lock your threads and wait for each other, but that way you just make like one-threaded program. It is some weird for me, can you explain more why you want this, why you need more threads if one is sufficient?

If you are doing this just to learn multi-threading then its fine, other wise as pointed out by previous post it surely is not a candidate for multithread programming.

I came up with this weird solution ... !
I don't know !

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

const char* string = "Animesh Pandey";
struct pass {
   char *str;
   int pos;
   int thr_no;
};

void *print1 (void* arg) {
   int n;
   n = (int) arg;

   printf("For Thread1 and %d : %c\n", n, string[n]);

   pthread_exit(NULL);
}

void *print2 (void* arg) {
   int n;
   n = (int) arg;

   printf("For Thread2 and %d : %c\n", n, string[n]);

   pthread_exit(NULL);
}

int main(void) {
   pthread_t thread1, thread2;
   int i;

   for (i=0; i<strlen(string); ++i) {
      if (i%2 == 0) {
         pthread_create (&thread1, NULL, print1, (void*)i);
      }
      else pthread_create (&thread2, NULL, print2, (void*)i);
   }
   
   pthread_join(thread1, NULL);
   pthread_join(thread2, NULL);

   return 0;
}

But the output is never same every time I run this program .... !
The sequence changes every time !
Is there a way I can get the output in the sequence I have mentioned earlier ... ?

Could you please suggest a better way to do this with two threads ... ?

Thanks

Moved: This thread is more suitable in Programming and has been moved accordingly to help your thread/question get the exposure it deserves.

You do not have direct control on the scheduling the kernel is doing. However, the thing you're aiming on is possible, you just need to use synchronization mechanisms. In pthread library, you can use a mutex, for instance. Read the documentation of:

int pthread_mutex_lock(pthread_mutex_t *mutex);
int pthread_mutex_unlock(pthread_mutex_t *mutex);

If you have more questions on how to use mutexes, let us know.