Function Overloading; Default Arguments; Inline Functions

Function Overloading

What is Function Overloading?

Functions having the same name but differing in:

• Number of arguments
• Type of arguments
• Order of arguments

This process is called function overloading.

// Multiple 'Add' functions
int Add(int a, int b, int c, int d) {
    return a + b + c + d;
}

float Add(float a, float b, float c, float d) {
    return a + b + c + d;
}

float Add(int a, float b, float c, float d) {
    return a + b + c + d;
}

float Add(int a, int b, float c, float d) {
    return a + b + c + d;
}

float Add(int a, float b, float c) {   // different count
    return a + b + c;
}

// Practical example
void print(int n) {
    cout << "Integer: " << n << endl;
}

void print(double d) {
    cout << "Double: " << d << endl;
}

void print(string s) {
    cout << "String: " << s << endl;
}

void print(int n, string label) {
    cout << label << ": " << n << endl;
}

int main() {
    print(42);           // Integer: 42
    print(3.14);         // Double: 3.14
    print("Hello");      // String: Hello
    print(42, "Answer"); // Answer: 42
    return 0;
}

Operator Overloading vs Function Overloading

Default Arguments

What are Default Arguments?

Default values assigned to function parameters that are used when no argument is provided.

Rules: Default arguments should be given in right-to-left order.

// Default arguments: right-to-left (mandatory rule!)
void display(int x, int y = 10, int z = 20) {   // y and z have defaults
    cout << "x=" << x << ", y=" << y << ", z=" << z << endl;
}

int main() {
    display(5);          // x=5, y=10, z=20 (both defaults used)
    display(5, 30);      // x=5, y=30, z=20 (z default used)
    display(5, 30, 40);  // x=5, y=30, z=40 (no defaults)
    return 0;
}

WRONG — Default args must be rightmost:

// ERROR: cannot have default args before non-default args
void wrong(int x = 5, int y) { }   // Compile error!

Real-World Default Arguments Example

void create_account(string name, double balance = 0.0,
                    string type = "Savings", bool active = true) {
    cout << "Account: " << name
         << ", Balance: " << balance
         << ", Type: " << type << endl;
}

int main() {
    create_account("Alice");                    // balance=0, type=Savings
    create_account("Bob", 5000.0);              // type=Savings
    create_account("Charlie", 10000.0, "Current"); // all provided
    return 0;
}

Inline Functions

What is an Inline Function?

An inline function is a function where the compiler replaces the function call with the function body — avoiding function call overhead.

• Small, frequently called functions benefit most
• Compiler may ignore inline hint

When compiler should NOT replace:

• Functions containing switch, loops

Recursive functions

inline float triangle_area(float base, float height) {
    return 0.5 * base * height;
}

// What the compiler does:
// Instead of: float area = triangle_area(10, 5);
// It
generates: float area = 0.5 * 10 * 5;

int main() {
    float base, height;
    cout << "Enter base: "; cin >> base;
    cout << "Enter height: "; cin >> height;
    cout << "Area: " << triangle_area(base, height) << endl;
    return 0;
}

Inline vs Macros