LESSON 278 OF 667 · FUNCTIONS & CLASSES

Member Variables in C++

Lesson

TL ; DR:

A member variable (or field) is a variable that lives inside a class. Each object of that class has its own copy.
Declare member variables under a public: access label so other code can read and write them:
```
class Dog {
public:
    string name;
    int age;
};
```
Access them on an object with the dot operator: dog.name = "Rex";

Full lesson:

Right now your Dog class is just an empty shell — every Dog object you create is identical. We need a way to attach data to each object.

That's what member variables are for. A member variable is a variable that belongs to a class — and each object created from that class gets its own copy of every member.

Declaring member variables

class Dog {
public:
    string name;
    int age;
};

public: is an access label — every member declared after it is accessible from outside the class. Without it, members default to private in a class.
string name; is a regular variable declaration.

Reading and writing

Dog dog;
dog.name = "Rex";        // write
dog.age = 4;
cout << dog.name << endl;  // read

Each object has its own slot for every member, so two dogs can have different names without interfering.

Your task

Update the Dog class to have two member variables: name (a string) and age (an int) under a public: label. Then in mainFunction, set them on the dog object so the pre-filled cout prints:

Rex is 4 years old

STEP 1 OF 2

Guided

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