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10-pupils.cpp
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99 lines (89 loc) · 2.91 KB
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// 10-pupils.cpp : use of shared_ptr and weak_ptr to avoid dependency cycle
#include <memory>
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <string_view>
using namespace std;
struct Pupil;
struct Class {
Class(int r, string_view s, string_view t)
: room{ r }, subject{ s }, teacher_name{ t } {}
int room;
string subject, teacher_name;
vector<shared_ptr<Pupil>> pupils;
};
struct Pupil {
Pupil(string_view n) : name{ n } {}
string name;
vector<weak_ptr<Class>> classes;
};
int main() {
vector<shared_ptr<Class>> AllClasses{
make_shared<Class>(101, "English", "Mr White"),
make_shared<Class>(150, "Math", "Miss Black")
};
vector<shared_ptr<Pupil>> AllPupils{
make_shared<Pupil>("Paul"),
make_shared<Pupil>("Percy"),
make_shared<Pupil>("Perry"),
make_shared<Pupil>("Phoebe"),
make_shared<Pupil>("Penny"),
make_shared<Pupil>("Patricia")
};
auto add_to_class = [&](string_view c, string_view p) {
auto iter_c = find_if(cbegin(AllClasses), cend(AllClasses),
[&](auto ec){ return c == ec->subject; });
auto iter_p = find_if(cbegin(AllPupils), cend(AllPupils),
[&](auto ep){ return p == ep->name; });
if (iter_c != cend(AllClasses) && iter_p != cend(AllPupils)) {
(*iter_c)->pupils.push_back(*iter_p);
(*iter_p)->classes.push_back(*iter_c);
}
else {
cerr << "Could not add " << p << " to " << c << '\n';
}
};
add_to_class("English", "Paul");
add_to_class("English", "Percy");
add_to_class("English", "Phoebe");
add_to_class("English", "Penny");
add_to_class("Math", "Paul");
add_to_class("Math", "Perry");
add_to_class("Math", "Phoebe");
add_to_class("Math", "Patricia");
AllClasses.emplace_back(make_shared<Class>(260, "IT", "Mrs Brown"));
add_to_class("IT", "Percy");
add_to_class("IT", "Perry");
for (const auto& c : AllClasses) {
cout << "Room: " << c->room << "\nSubject: " << c->subject
<< "\nTeacher: " << c->teacher_name << "\nPupils: ";
for (const auto& p : c->pupils) {
cout << p->name << ' ';
}
cout << '\n';
}
for (;;) {
cout << "Please enter a pupil name (blank line to quit): ";
string s;
getline(cin, s);
if (s.empty()) {
break;
}
auto iter_p = find_if(cbegin(AllPupils), cend(AllPupils),
[&](auto ep){ return s == ep->name; });
if (iter_p != cend(AllPupils)) {
cout << "Classes: ";
for (const auto& c : (*iter_p)->classes) {
if (auto pc = c.lock(); pc) {
cout << pc->subject << ' ';
}
}
cout << '\n';
}
else {
cout << "Name not recognized!\n";
}
}
}