Structs

A struct groups related data under one name. A player has a name and health, so instead of defining two separate variables for every player, you write struct Player { std::string name; int hp = 100; };, and don't forget the semicolon after the closing brace. You create a player by listing the values in the order of the fields, like Player hero{"Layan", 80};, and any field you leave out takes its default value, so the player Player hero{"Layan"}; has 100 HP. You reach the fields with a dot, as in hero.hp -= 10;.

You can also write functions inside the struct that work on its fields directly. These are called member functions: inside takeDamage, hp means this player's own health, and you call it with a dot, as in hero.takeDamage(30);. The word const after the parentheses in bool alive() const is a promise that the function doesn't change the object, and on a const Player& you can only call functions that make this promise. So a function that reads the team as const std::vector<Player>& can't call alive() unless it's const.

The benefit is that the rule stays with the data: health never drops below zero, because damage goes through takeDamage, which prevents it. But the fields of a struct are exposed, and nothing stops code outside it from writing hero.hp = -50;. That's what the next lesson deals with.