Linux_cmd_lab #3

#include<iostream>
#include<vector>
#include<unistd.h>
#include<string.h>

using namespace std;

void help(){
  cout << "Chebeshev function\nn - number of iteration\nx - argument of function\nPlease, enter the value of n and x.\n Use Enter for it\n";
}

int enter_n() {
  int n;
  cin >> n;
  cin.clear();
  while (cin.get() != '\n'){
    cout << "Error. Try again" << endl;
    enter_n();
  }
return n;
}

double enter_x() {

  double x;
  cin >> x;
  cin.clear();
 while (cin.get() != '\n'){
    cout << "Error. Try again" << endl;
    cin.clear();
    enter_x();
  }

return x;
}


double chebeshev(int n, double x)
{
   if (n == 0)
           {
                 return 1;
           }
           else if (n == 1)
           {
                 return x;
           }
           else
           {
                 double polinom;
                 polinom = 2 * x * chebeshev(n - 1, x) - chebeshev(n - 2, x);
                 return polinom;
           }
    }
int main(int argc, char ** argv){
if ((argc == 2) && (!strcmp("help", argv[1])))
    {
        help();
        exit(0);
    }
int pid;
int c[2];
int s[2];
pipe(c);
pipe(s);
if((pid = fork()) == -1)
           {
                   perror("fork");
                   exit(1);
           }
        if((pid = fork()) == 0)
           {

                int n = enter_n();

                write(c[1], &n, sizeof(n));
                int x = enter_x();
                write(c[1], &x, sizeof(x));
                close(c[1]);

        double result1;
                read(s[0], &result1, sizeof(result1));
                close(s[1]);
                cout << "Result = " << result1 << endl;

           }
           else
           {
                int n1;

                read(c[0], &n1, sizeof(n1));
                int x1;
                read(c[0], &x1, sizeof(x1));
                close(c[0]);

                double result =  chebeshev(n1, x1);
                write(s[1], &result, sizeof(result));
                close(s[1]);

           }
    return 0;
}