Programming

#include <iostream>
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#include <wait.h>
using namespace std;

#define READ 0
#define WRITE 1

int main(){
	int n1, n2, res, buf1, buf2, p1[2], p2[2], p3[2];
	pid_t pp;
	pipe(p1);
	pipe(p2);
	pipe(p3);

	pp=fork();

	if (pp==-1){ //error
	perror("fork");
	cout << "error n = " << errno << endl;
	return 0;}

	if (pp!=0){ //father
		cout << endl << "FATHER(" << (int)getpid() << "): type a number: ";
		cin >> n1;
		cout << endl << "FATHER(" << (int)getpid() << "): type a number: ";
		cin >> n2;

		cout << endl << "FATHER(" << (int)getpid() << "): I will send those numbers to my child process to multiply them." << endl;

		close(p1[READ]);
		write(p1[WRITE],&n1,sizeof(n1));
		close(p1[WRITE]);

		close(p2[READ]);
		write(p2[WRITE],&n2,sizeof(n2));
		close(p2[WRITE]);
	}

	if(pp==0){ //child
		close(p1[WRITE]);
		read(p1[READ],&buf1,sizeof(buf1));
		close(p1[READ]);

		close(p2[WRITE]);
		read(p2[READ],&buf2,sizeof(buf2));
		close(p2[READ]);

		cout << endl << "CHILD(" << (int)getpid() << "): Yay, father process sent me two numbers: " << buf1 <<" and " << buf2 << "." << endl;

		buf1=buf1*buf2;

		cout << endl << "CHILD(" << (int)getpid() << "): I will multiply them and send back: " << buf1 << "." << endl;

		close(p3[READ]);
		write(p3[WRITE],&buf1,sizeof(buf1));
		close(p3[WRITE]);
		exit(0);
	}
	close(p2[WRITE]);
	read(p2[READ],&res,sizeof(res));
	close(p2[READ]);
	wait(&pp);
	cout << endl << "FATHER(" << (int)getpid() << "): Child process sent me back the result: " << res << "." << endl;

	return 0;
}

	close(p2[WRITE]);
	read(p2[READ],&result,sizeof(result));
	close(p2[READ]);
	cout << endl << "Child process send me back the result: " << result << "." << endl;