Class Methods

Overview

Methods can be defined directly inside the class (automatically made inline), or declared inside and defined outside using the Scope Resolution Operator `::`. This keeps class definitions clean.

Syntax

cpp

class Math {
public:
    // Defined inside
    int add(int a, int b) { return a + b; }
    
    // Declared inside
    int multiply(int a, int b); 
};

// Defined outside using ClassName::
int Math::multiply(int a, int b) {
    return a * b;
}

Common Pitfalls

Forgetting the `ClassName::` prefix when defining outside, which accidentally creates a global function instead of a class method.

Interview Tips

In professional codebases, class declarations go into Header files (.h or .hpp), and the outside definitions go into Source files (.cpp). This speeds up compilation times significantly.

Real-World Example

Defining a complex method outside the class for readability.

example

cpp

#include <iostream>
using namespace std;

class User {
public:
    string name;
    void printDetails(); // Prototype
};

// Clean outside definition
void User::printDetails() {
    cout << "User details processing..." << endl;
    cout << "Name: " << name << endl;
}

int main() {
    User u;
    u.name = "Alice";
    u.printDetails();
    return 0;
}

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