Linux Shared Memory Segmentation Fault

I am leaing about shared memory and have created this sample program to test things out

//IPC - Shared Memory

#include<stdio.h>
#include<stdlib.h>
#include<linux/ipc.h>
#include<linux/msg.h>
#include<linux/shm.h>

int main(int argc, char* argv[])
{
  printf("setting up shared memoryn");

  key_t ipc_key;
  int shmid;
  int pid;


  ipc_key = ftok(".",'b');

  if((shmid=shmget(ipc_key, 32, IPC_CREAT|0666))==-1)
  {
    printf("error creating shared memoryn");
    exit(1);
  }

  printf("shared memory created with id %dn",shmid);

  //fork a child process
  pid = fork();
  printf("fork result %dn",pid);
  if(pid==0)
  {
    //child process
    //attach the shared memory
    int* shm_add_child = (int*)shmat(shmid, 0,0);
    printf("child attached to shared mem at address %pn",(void*)shm_add_child);

    while(1)
    {
      printf("%dn",*shm_add_child);
      printf("an");
    }

    //detach from shm
    shmdt(shm_add_child);
  }
  else
  {
    //parent process
    int* shm_add_parent;

    shm_add_parent = (int*)shmat(shmid, 0,0);
    printf("parent attached to shared mem at address %pn",(void*)shm_add_parent);
    *shm_add_parent = 10;

    sleep(10);

    //detach from shm
    shmdt(shm_add_parent);
  }

  //remove shm
  shmctl(shmid, IPC_RMID,0);

  exit(0);
}

However when I run it, I get segmentation fault. It seems that my pointers to the shared memory are not right. Also nothing is getting printed from the indefinite while loop in the child process.

ankit@ankit-ThinkPad-W530:~/Desktop/week1_tasks$ ./ipc_sharedmem_a 
setting up shared memory
shared memory created with id 5996570
fork result 8703
parent attached to shared mem at address 0xffffffff991aa000
fork result 0
child attached to shared mem at address 0xffffffff991aa000
Segmentation fault (core dumped)

What is going wrong here?