synchronize processes

[emilio]

i am trying to synchronize between father process and son process
created by fork() command, to print simultaneously.

my program is written in c under bash shell.
the compile goes ok but when i try to run nothing happens and the program doesnot end.

my code is:

#include <stdio.h>
#include <semaphore.h>
#include <stdlib.h>
main() {
  sem_t s1;
  sem_t s2;
  int value1 , value2;

  sem_init(&s1, 0, 1);
  sem_init(&s2,0,1);
 
  sem_wait(&s2);
  
  
  int pid = fork();
  
  
  if (pid != 0)
  	{
  		int i;
  		for (i=0 ; i<=10 ; i++)
  		{
  			sem_getvalue (&s1,&value1);
  			while (value1 != 1)
  			  sem_getvalue (&s1,&value1);
  			  
  			sem_wait(&s1);
  			if (i%2 != 0)
  				printf("%d\n",i);
  				
  			sem_post(&s2);
  		}
  	}
  	
  	
  	if (pid == 0)
  	{
  		int j;
  		for (j=0 ; j<=10 ; j++)
  		{
  			sem_getvalue (&s2,&value2);
  			while (value2 != 1)
  			  sem_getvalue (&s2,&value2);
  			  
  			sem_wait(&s2);
  			if (j%2 == 0)
  				printf("%d\n",j);
  				
  			sem_post(&s1);	  
  		}
  		exit(0);
  	}
  
  
  
 return 0;
}

is there any other way to synchronize father and son process ?