Question

This is my CreateCustomer method:

CustomerData Database::createCustomer(std::string const& name) {
    CustomerData data(customersDb.size()+1, name);
    customersDb[data.number()] = data;
//    customersDb.insert(std::pair<uint, CustomerData>(data.number(), data));
    return data;
}

Constructor of class CustomerData:

CustomerData::CustomerData(uint number, std::string const& name) {
    m_number = number;
    m_name = name;
}

Incorrect line is this one:

customersDb[data.number()] = data;

Thing is, the next line works. I can’t figure it out and can’t use insert because accessing element with [] brackets doesn’t work either.

I’ve tried even creating copy constructor but with no effect:

CustomerData::CustomerData(CustomerData &data) {
    m_number = data.number();
    m_name = data.name();
}

These are the errors:

Database.cpp:5: instantiated from here
stl_map.h:450: error: no matching function for call to 'CustomerData::CustomerData()'
CustomerData.h:18: candidates are: CustomerData::CustomerData(CustomerData&)
CustomerData.h:17: note: CustomerData::CustomerData(uint, const std::string&)

I use Mingw.

Answer 1

operator[] with the standard map template default-constructs an element with the given key if none already exists.

Your element type has no default constructor, so this cannot happen.

You’ll have to use .insert instead.

customersDb.insert(make_pair(data.number(), data));

I can’t figure it out and can’t use insert because accessing element with [] brackets doesn’t work either.

To modify an existing element, retrieve an iterator with .find, dereference and do your thing.

yourMapType::iterator it = customersDb.find(data.number());
if (it != customersDb.end())
   *it = data;