UNIX for Beginners Questions & Answers

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <unistd.h>

int main()
{ int pipefd[2];
  int pipefe[2];
  int pipeff[2];
  pipe(pipefd);
  pipe(pipefe);
  pipe(pipeff);

  char arr[80];
  scanf("%s", arr);
  int f1 = fork();
  
  if(f1>0)
	{close(pipefd[0]);
	 close(pipefe[0]);
	 close(pipeff[0]);
	 if (arr[0]>='A'&&arr[0]<='z')
		{
         	write(pipefd[1], arr, strlen(arr)+1);
	 	close(pipefd[1]);
		}
	if(arr[0]>='0' && arr[0]<='9')
		{
		write(pipefe[1], arr, strlen(arr)+1);
	 	close(pipefe[1]);
		}
	else
	   {
	    write(pipeff[1], arr, strlen(arr)+1);
	    close(pipeff[1]);
	   }
         exit(0);
	}
   else if(fork()==0)
     { wait(NULL);
       close(pipefd[1]);
       read(pipefd[0], arr, strlen(arr)+1);
       printf("%s\n", arr);
       close(pipefd[0]);
       exit(0);
     }
   else if(fork()==0)
     { wait(NULL);
       close(pipefe[1]);
       read(pipefe[0], arr, strlen(arr)+1);
       printf("%s\n", arr);
       close(pipefe[0]);
       exit(0);
     }
   else if(fork()==0)
     { wait(NULL);
       close(pipeff[1]);
       read(pipeff[0], arr, strlen(arr)+1);
       printf("%s\n", arr);
       exit(0);
       return 0;
     }

}

 else if(fork()==0)

else  
{ mypid1 = fork();
  if (mypid!=0 ) 
  {
    // do something 
  }
}

pid_t pid=fork();

if(pid < 0)
{
    perror("couldn't fork");
    exit(1);
}

if(pid == 0) {
        // Child code
        do_stuff();
        exit(0);
}

// Parent code