---
description: C++ is an object-oriented programming language.
---

# Implementation

Everything in C++ is associated with classes and objects, along with its attributes and methods. For example: in real life, a car is an **object**. The car has **attributes**, such as weight and color, and **methods**, such as drive and brake.

Attributes and methods are basically **variables** and **functions** that belongs to the class. These are often referred to as "class members".

A class is a user-defined data type that we can use in our program, and it works as an object constructor, or a "blueprint" for creating objects.

### Create a Class

To create a class, use the `class` keyword:

{% code title="Create a class called "MyClass":" %}
```cpp
class MyClass {       // The class
  public:             // Access specifier
    int myNum;        // Attribute (int variable)
    string myString;  // Attribute (string variable)
};
```
{% endcode %}

#### Example explained

* The `class` keyword is used to create a class called `MyClass`.
* The `public` keyword is an **access specifier**, which specifies that members (attributes and methods) of the class are accessible from outside the class. Take a look at this  [**access specifiers**](https://www.w3schools.com/cpp/cpp_access_specifiers.asp).
* Inside the class, there is an integer variable `myNum` and a string variable `myString`. When variables are declared within a class, they are called **attributes**.
* At last, end the class definition with a semicolon `;`

<details>

<summary>Create an Object</summary>

In C++, an object is created from a class. We have already created the class named `MyClass`, so now we can use this to create objects.

To create an object of `MyClass`, specify the class name, followed by the object name.

To access the class attributes (`myNum` and `myString`), use the dot syntax (`.`) on the object:

```cpp
class MyClass {       // The class
  public:             // Access specifier
    int myNum;        // Attribute (int variable)
    string myString;  // Attribute (string variable)
};

int main() {
  MyClass myObj;  // Create an object of MyClass

  // Access attributes and set values
  myObj.myNum = 15; 
  myObj.myString = "Some text";

  // Print attribute values
  cout << myObj.myNum << "\n";
  cout << myObj.myString;
  return 0;
}
```

</details>

## [**Practice Exercise**](https://www.w3schools.com/cpp/exercise.asp?filename=exercise_classes2)

## **Class Methods**

Methods are **functions** that belongs to the class.

There are two ways to define functions that belongs to a class:

* Inside class definition
* Outside class definition

In the following example, we define a function inside the class, and we name it "`myMethod`".

**Note:** You access methods just like you access attributes; by creating an object of the class and using the dot syntax (`.`):

<details>

<summary>Inside Class</summary>

```cpp
class MyClass {        // The class
  public:              // Access specifier
    void myMethod() {  // Method/function defined inside the class
      cout << "Hello World!";
    }
};

int main() {
  MyClass myObj;     // Create an object of MyClass
  myObj.myMethod();  // Call the method
  return 0;
}
```

</details>

<details>

<summary>Outside Class</summary>

To define a function outside the class definition, you have to declare it inside the class and then define it outside of the class. This is done by specifiying the name of the class, followed the scope resolution `::` operator, followed by the name of the function:

```cpp
class MyClass {        // The class
  public:              // Access specifier
    void myMethod();   // Method/function declaration
};

// Method/function definition outside the class
void MyClass::myMethod() {
  cout << "Hello World!";
}

int main() {
  MyClass myObj;     // Create an object of MyClass
  myObj.myMethod();  // Call the method
  return 0;
}
```

</details>
