An object and its member functions

Account acct{"Ada", 100}; runs the constructor, which fills in the private fields. When deposit runs, its frame has this, a pointer to acct: that's how a member function knows which object it's working on.

#include <iostream>
#include <string>

class Account {
public:
    Account(std::string owner, int balance) : owner_(owner), balance_(balance) {}
    void deposit(int amount) {
        balance_ += amount;
    }
    int balance() const { return balance_; }

private:
    std::string owner_;
    int balance_;
};

int main() {
    Account acct{"Ada", 100};
    acct.deposit(50);
    std::cout << acct.balance() << "\n";
    return 0;
}

Output:

From the lesson: Classes