Не находит freopen

\day2\theatre\solutions\theatre_vg_easy.cpp|80|error: 'freopen' was not declared in this scope|

#include <iostream>
 
using namespace std;
 
struct computer_desktop {
    string cpu_type;
    int cpu_speed;
    int price;
    int hard_disk_capacity;
    string graphics_card_type;
};
 
void create_desktop() { 
                        freopen("filex.txt","r",stdin);
            cout << "Enter cpu type" << endl;
            cin >> a[n].cpu_type;
            cout << "Enter Price of computer" << endl;
            cin >> a[n].price;
            cout << "Enter Cpu speed of computer" << endl;
            cin >> a[n].cpu_speed;
            cout << "Enter hard disk capacity" << endl;
            cin >> a[n].hard_disk_capacity;
            cout << "Enter Graphics card type" << endl;
            cin >> a[n].graphics_card_type;
            n++;
}
 
int main() {
    while(true) {
        freopen("computers.txt", "r", stdin);
        char ch;
        cout << "Create new computer, enter 'c':" << endl;
if (ch == 'c') {
            cout<<"If you want to create desktop,enter d,if laptop enter l"<<endl;
            cin>>dh;
            if(dh=='d'){
                create_desktop();
            }
            else if(dh=='l'){
                    create_laptop();
                }
        }

#include <fstream>
#include <iostream>
#include <string>
 
using namespace std;
 
struct computer_desktop {
    string cpu_type;
    string graphics_card_type;
};
 
computer_desktop create_desktop(std::istream &input)
{
    computer_desktop obj;
    input >> obj.cpu_type >> obj.graphics_card_type;
    return obj;
}
 
int main()
{
    std::ifstream input_desktop("desktop.txt");
    std::ifstream input_laptop("laptop.txt");
    if (!input_desctop || !input_laptop)
        return 1;
 
    computer_desktop cd = create_desktop(input_desktop);
}