Pass the value from child process to parent process

Prerequisite: Pipe() and Fork() Basic
Write a C program in which the child process takes an input array and send it to the parent process using pipe() and fork() and then print it in the parent process.

Examples: Suppose we have an array a[]={1, 2, 3, 4, 5} in child process, then output should be 1 2 3 4 5.

Input:  1 2 3 4 5
Output: 1 2 3 4 5

// C program for passing value from
// child process to parent process
#include <pthread.h>
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>
#define MAX 10

int main()
{

  int fd[2], i = 0;
  pipe(fd);
  pid_t pid = fork();

   if(pid > 0) {
      wait(NULL);

      // closing the standard input
      close(0);

      // no need to use the write end of pipe here so close it
      close(fd[1]);

       // duplicating fd[0] with standard input 0
      dup(fd[0]);
      int arr[MAX];

      // n stores the total bytes read successfully
      int n = read(fd[0], arr, sizeof(arr));
      for ( i = 0;i < n/4; i++)

         // printing the array received from child process
          printf("%d ", arr[i]);
  }
  else if( pid == 0 ) {
      int arr[] = {1, 2, 3, 4, 5};

      // no need to use the read end of pipe here so close it
      close(fd[0]);

       // closing the standard output
      close(1);

      // duplicating fd[0] with standard output 1
      dup(fd[1]);
      write(1, arr, sizeof(arr));
  }

  else {
      perror("error\n"); //fork()
  }
}

Steps for executing above code:

• To compile, write gcc program_name.c
• To run, write ./a.out