How to Create Class in C++: Syntax and Example

In C++, you create a class using the class keyword followed by the class name and curly braces containing members. Members can be variables and functions that define the class behavior. Use public: to make members accessible outside the class.

Syntax

A class in C++ is defined using the class keyword, followed by the class name and a pair of curly braces { }. Inside, you declare variables (called data members) and functions (called member functions). Access specifiers like public: control which members are accessible from outside the class.

• class: keyword to define a class
• ClassName: the name you give your class
• public: members accessible from outside
• private: members accessible only inside the class (default)
• data members: variables that hold data
• member functions: functions that operate on data

cpp

class ClassName {
public:
    // public members
private:
    // private members
};

Example

This example shows how to create a simple Car class with a public data member and a member function to display its value.

cpp

#include <iostream>
using namespace std;

class Car {
public:
    string brand;
    void showBrand() {
        cout << "Car brand: " << brand << endl;
    }
};

int main() {
    Car myCar;
    myCar.brand = "Toyota";
    myCar.showBrand();
    return 0;
}

Output

Car brand: Toyota

Common Pitfalls

Beginners often forget to add a semicolon ; after the class definition, which causes a compilation error. Another common mistake is not specifying public: before members, making them private by default and inaccessible outside the class.

Also, trying to access private members directly from outside the class will cause errors.

cpp

/* Wrong: Missing semicolon after class */
class Person {
public:
    string name;
}; // <-- added missing semicolon here

/* Wrong: Members are private by default */
class Person {
    string name; // private by default
};

int main() {
    Person p;
    // p.name = "Alice"; // Error: 'name' is private
}

/* Right: Add semicolon and public access */
class Person {
public:
    string name;
};

int main() {
    Person p;
    p.name = "Alice"; // Works fine
}

Quick Reference

• Use class ClassName { ... }; to define a class.
• Members are private by default; use public: to expose them.
• Always end class definition with a semicolon ;.
• Access members with dot . operator on objects.
• Use member functions to interact with private data safely.

Key Takeaways

Define a class with the class keyword followed by its name and curly braces.

Members are private by default; use public: to make them accessible outside.

Always end your class definition with a semicolon ; to avoid errors.

Use objects and the dot operator to access public members and functions.

Member functions help safely access or modify private data inside the class.