Member functions

Learn to define member functions (methods) in a class.

Member functions

Functions declared in a class body are called member functions. They define the object's behavior. In a Counter class, void increment() { count++; } is a member function.

Member functions can access other members of the class directly: you just write count, no need for this->count. Calls use a dot: counter.increment();. Member functions defined inside the class body are treated as inline.

Return value and parameters

Member functions can return a value and take parameters, just like free functions. Example: int add(int x) { return count + x; }. Here int is the return type and x is a parameter.

A void function returns no value; return is omitted or used only to end the flow. Functions that return a value must have a return statement in their body. You can assign the returned value to a variable or print it directly.

Exercise Add a member function to the Counter class

Define a Counter class. Under public: add int count; and the member function void increment() { count++; }. In main create an instance, call increment and print count with std::cout.

Show example solution

#include <iostream>

class Counter {
public:
    int count;
    void increment() {
        count++;
    }
};

int main() {
    Counter counter;
    counter.count = 0;
    counter.increment();
    std::cout << counter.count;
    return 0;
}

Test yourself

Match each piece to its role

void increment()

Member function declaration
counter.increment()

Member function call
int count;

Member variable
class Counter { };

Class definition

Complete the return statement

int getValue() { ____ value; }

Show answer

int getValue() { return value; }

What does counter.increment(); do?
```
Counter counter;
```
- Redefines the class
- Deletes a member variable
- Calls the increment member function
- Creates a new instance
Show answer

Deletes a member variable — The dot calls a member function.

Next lesson: The this pointer

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