I have a class Carmodel, also I have a database - map container: map<string, set<CarModel>> where string type is for a company name and set contains CarModels Name.
I want to write a method which could delete a Car for the exact Company. But I don't know how.
In example, I have a company Ferrari in database, and this company have a set of car models, like California, Barionetta and etc. Imagine I write in console Del Ferrari California. How do I erase a California from a set of Car models?
// Add - Add a new company with a car (name, type, powervalue);
// Print - if arguments are empty, prints all the database. Also available:
// Print "companyname" (to print all models for this company)
// Print "cartype" - print all cars with this type
// Print "carname" - print an information about car;
#include <iostream>
#include <string>
#include <vector>
#include <map>
#include <sstream>
#include <exception>
#include <set>
#include <iomanip>
#include <sstream>
using namespace std;
class CarModel
{
public:
CarModel (const string& new_name, const string& new_type, const int& new_powerValue)
{
if (new_name.size() > 12 || new_name.empty())
{
throw out_of_range("Model name is incorrect: " + new_name);
}
else if (new_type.size () > 8 || new_type.empty())
{
throw out_of_range("Type name is incorrect " + new_type);
}
else if (new_powerValue > 2500 || new_powerValue < 250)
{
throw out_of_range("Powe Value is incorrect " + to_string(new_powerValue));
}
name = new_name;
type = new_type;
powerValue = new_powerValue;
}
string GetCarModelName () const
{
return name;
}
string GetCarType () const
{
return type;
}
int GetCarPowerValue () const
{
return powerValue;
}
private:
string name;
string type;
int powerValue;
};
ostream& operator << (ostream& stream, const CarModel& carmodel)
{
stream << carmodel.GetCarModelName() << ' ' << carmodel.GetCarType()
<< ' ' << carmodel.GetCarPowerValue() << " hp";
return stream;
}
bool operator < (const CarModel& r, const CarModel& l)
{
return (r.GetCarModelName() < l.GetCarModelName());
}
class Database
{
public:
void AddCompanyModel (const string& company, const CarModel& carmodel)
{
database[company].insert(carmodel);
}
int CheckString (const string& sinput) const
{
for (const auto& k : database)
{
if (k.first == sinput)
{
return 1;
}
else
{
for (const auto& i : k.second)
{
if (i.GetCarType() == sinput)
{
return 2;
}
else if (i.GetCarModelName() == sinput)
{
return 3;
}
}
}
}
return 4;
}
void PrintAllModels() const
{
if (database.empty())
{
cout << "No models in database" << endl;
}
for (const auto& i : database)
{
cout << i.first << ": ";
unsigned int s = 0;
for (const auto& k : i.second)
{
++s;
if (s < i.second.size())
{
cout << k.GetCarModelName() << ", ";
}
else if ( s == i.second.size())
{
cout << k.GetCarModelName();
}
}
cout << endl;
}
}
void PrintCompany (const string& companyname) const
{
if (database.count(companyname) == 0)
{
cout << "No company in database with name: " + companyname << endl;
}
else
{
for (const auto& k : database)
{
if (k.first == companyname)
{
unsigned int s = 0;
for (const auto& i : k.second)
{
++s;
if (s < k.second.size())
{
cout << i.GetCarModelName() << ", ";
}
else if( s == k.second.size())
{
cout << i.GetCarModelName();
}
}
cout << endl;
}
}
}
}
void PrintType(const string& sinput) const
{
vector <string> typebase;
for (const auto& k : database)
{
for (const auto& i : k.second)
{
if (i.GetCarType() == sinput)
{
typebase.push_back(i.GetCarModelName());
}
}
}
cout << sinput << ": ";
unsigned int x = 0;
for (const auto& s : typebase)
{
++x;
if ( x < typebase.size())
{
cout << s << ", ";
}
else if ( x == typebase.size())
{
cout << s;
}
}
cout << endl;
}
void PrintCarInformation (const string& sinput) const
{
for (const auto& k : database)
{
for (const auto& i : k.second)
{
if (i.GetCarModelName() == sinput)
{
cout << i.GetCarModelName() << " made by" << k.first << " with " << i.GetCarType() << " type " << " and " << i.GetCarPowerValue() << "hp" << endl;
}
}
}
}
bool DeleteCompany (const string& _companyname)
{
for (const auto& k : database)
{
if (k.first == _companyname)
{
database.erase(_companyname);
return true;
}
else
{
return false;
}
}
return false;
}
int DeleteCarMOdel (const string& _companyname, const string& _carmodel)
{
for (const auto& k : database)
{
if (k.first == _companyname)
{
for (const auto& i : k.second)
{
if (i.GetCarModelName() == _carmodel)
{
set<CarModel>::iterator it = k.second.find(i.GetCarModelName());
}
}
}
}
}
private:
map<string, set<CarModel>> database;
};
//void ValidNextCharAndSkip (stringstream& s, const string& carmodel)
//{
// if (s.peek() != ' ')
// {
// throw logic_error("Wrong format in: " + carmodel);
// }
// s.ignore(1);
//}
CarModel ParseCarModel (const string& carmodel, const string& cartype, const int& powerValue)
{
stringstream car_stream(carmodel);
stringstream car_type(cartype);
string name, type;
car_stream >> name;
// ValidNextCharAndSkip(car_stream, carmodel);
car_type >> type;
// ValidNextCharAndSkip(car_stream, carmodel);
return { name, type, powerValue };
}
int main()
{
try
{
Database base;
string command;
while(getline(cin,command))
{
stringstream stream(command);
string operation;
stream >> operation;
if (operation == "Add")
{
string _companyname, _carName, _carType;
int _carPowerValue;
stream >> _companyname >> _carName >> _carType >> _carPowerValue;
const CarModel car = ParseCarModel(_carName, _carType, _carPowerValue);
base.AddCompanyModel(_companyname, car);
}
else if (operation == "Print")
{
string sinput;
stream >> sinput;
if (sinput.empty())
{
base.PrintAllModels();
}
else
{
if (base.CheckString(sinput) == 1)
{
base.PrintCompany(sinput);
}
else if (base.CheckString(sinput) == 2)
{
base.PrintType(sinput);
}
else if (base.CheckString(sinput) == 3)
{
base.PrintCarInformation(sinput);
}
else if (base.CheckString(sinput) == 4)
{
cout << "No such a type or a company in database: " + sinput << endl;
}
}
}
else if (operation == "Del")
{
string _companyname, _carname;
stream >> _companyname;
if (!stream.eof())
{
stream >> _carname;
}
if (_carname.empty())
{
if (base.DeleteCompany(_companyname))
{
cout << _companyname << " was deleted successfully" << endl;
}
else
{
cout << "Company named " << _companyname << " not found" << endl;
}
}
}
else if (!operation.empty())
{
throw logic_error("Unknown command: " + command);
}
}
} catch (exception& ex) {
cout << ex.what() << endl;
}
return 0;
}
Know your containers better!
One reason you might want to use a map or a set, besides unique key values and automatic sorting, is logarithmic complexity key retrieval. You should never loop through them to see if you have a specific key.
In your DeleteCarModel, you should not use for (const auto& k : database) .... You have two options:
if(database.find(_companyname) != database.end())
{
database[_companyname] ...
}
or
database.at(_companyname) ...
Both of them gives you direct access to the underlying set, whereas the second one throws out_of_range exception when the key was not found. I'm only suggesting this because you already used some exception handling in your earlier code.
Then you can use set.erase to remove the specific car model:
if(database.find(_companyname) != database.end())
{
database[_companyname].erase(_carmodel);
}
or
database.at(_companyname).erase(_carmodel);
Update:
However this solution only works if _carmodel is actually of CarModel type, which is not the case. _carmodel is actually a string here.
In order to find a specific key in a map/set with a value of not the key type, you would first define couple custom operator<s:
bool operator<(const string& lhs, const CarModel& rhs)
{ return lhs < rhs.GetCarModelName(); }
bool operator<(const CarModel& lhs, const string& rhs)
{ return lhs.GetCarModelName() < rhs; }
bool operator<(const CarModel& lhs, const CarModel& rhs)
{ return lhs.GetCarModelName() < rhs.GetCarModelName(); }
Then you can set a Compare::is_transparent flag by specifying std::less<> for comparison when creating the databse :
map<string, set<CarModel, std::less<>>> database;
Now set.find works with string:
if(auto company_it = database.find(_companyname); company_it != database.end())
{
if(auto carmodel_it = company_it->second.find(_carmodel); carmodel_it != company_it->second.end())
{
company_it->erase(carmodel_it);
}
}
Or if you are using c++14 or earlier:
auto company_it = database.find(_companyname);
if(company_it != database.end())
{
auto carmodel_it = company_it->second.find(_carmodel);
if(carmodel_it != company_it->second.end())
{
company_it->second.erase(carmodel_it);
}
}