Error creating a size for a vector of Structs C++

Question

This is for a project I am doing for my college class and I could not find an answer for this that worked for me anywhere. Its very likely I did not understand the answers thou

Answer 1

For class members, you do not initialise them where you declare them (as the list of members is just that: a list of types and names), but instead in the constructor's member initialisation list.

Like this:

class Menu
{
    std::vector<menuItem> mi;    // no initialiser here

    Menu() : mi(20) {};          // but in the ctor-initializer instead
};

Answer 2

You're trying to pass parameters to a constructor of a non-static class member as part of the declaration, which is wrong.

Basically, you'll have to declare the data member in the declaration like this:

std::vector<menuitem> mi;

and as part of the constructor, call the appropriate resize, if that is even necessary.

Unless you know you need a minimum vector size of 20, I would forget about pre-sizing it and just let it grow as necessary.

Answer 3

You can do this in C++11 like so

class Menu
{
private:
    std::vector<menuItem> mi = std::vector<menuItem>(20);
};

or if you are stuck using C++03 you will need to initialize it in the constructors initializer list

class Menu
{
public:
    Menu() : mi(20) {}

private:
    std::vector<menuItem> mi;
};