Alice Alice - 1 month ago 13
C++ Question

No match for ‘operator<<’ when trying to print vector element

I am making a text based adventure game called Magick.

In this game I have a class labeled

damageSpell
it looks like this

class damageSpell {
public:
int damage;
SubClasses type;
int manaCost;
std::string spellDescription;
};


I used this class as the type for a vector like so

std::vector<damageSpell> damageSpells


Later on, I attempted to add an element into my
damageSpells
vector, by using the
insert
function on vector.

damageSpell fireball;

user.damageSpells.insert(user.damageSpells.begin(), 0, fireball);


Then attempted to print it out

std::cout << user.damageSpells[0];


Upon doing this I received this error


magick1.cpp:252:15: error: no match for ‘operator<<’ (operand types are ‘std::ostream {aka std::basic_ostream}’ and ‘damageSpell’)


I am new to C++ and have no idea what this means or how I should go about fixing it, any and all help will be appreciated.

Answer

user.damageSpells[0] is an instance of your class spellDamage. And your compiler doesn't have any idea of how to print it. You have to define a function that will be called on << operator and will print it out.

This operator overloading can be defined like this:

std::ostream& operator<<(std::ostream& stream, const damageSpell& damageSpellToPrint)
{
    // Your code here
}

It will be called eachtime you use << operator between a std::ostream (like std::cout) and an instance of your class. For instance, the following code will directly call your operator function, passing std::cout as stream parameter and user.damageSpells[0] as damageSpellToPrint parameter:

std::cout << user.damageSpells[0];

I suggest you this post or this documentation that will help you to understand operator overloading concepts in C++.

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