Default Arguments and Function Overloading0%

Default Arguments and Function Overloading

Beginner12 min read•Updated: 2026-10-22

🤹 Default Arguments and Function Overloading

Introduction

C++ enables polymorphism at compile time through function overloading (multiple functions sharing the same name with different parameter signatures) and default arguments.

⚙️ Default Arguments

Default arguments let callers omit parameters, substituting predefined defaults:

1#include <iostream>
2 
3// Note: Default arguments must be placed at the end of parameter list
4void printReceipt(double amount, double discountPercent = 0.0, double taxRate = 18.0) {
5    double discounted = amount - (amount * (discountPercent / 100.0));
6    double finalTotal = discounted + (discounted * (taxRate / 100.0));
7 
8    std::cout << "Base: ₹" << amount << " | Final Payable: ₹" << finalTotal << "\n";
9}
10 
11int main() {
12    printReceipt(1000);              // Uses default discount (0%) and tax (18%)
13    printReceipt(1000, 10.0);        // Uses 10% discount and default tax (18%)
14    printReceipt(1000, 10.0, 5.0);   // Overrides both discount and tax
15    return 0;
16}

🔄 Function Overloading

Functions can share an identical identifier as long as their parameter types or counts differ:

1#include <iostream>
2#include <string>
3 
4// Overload 1: Integers
5int calculateSum(int a, int b) {
6    return a + b;
7}
8 
9// Overload 2: Doubles
10double calculateSum(double a, double b) {
11    return a + b;
12}
13 
14// Overload 3: Three numbers
15int calculateSum(int a, int b, int c) {
16    return a + b + c;
17}
18 
19int main() {
20    std::cout << "Sum (int): " << calculateSum(10, 20) << "\n";
21    std::cout << "Sum (double): " << calculateSum(5.5, 4.2) << "\n";
22    std::cout << "Sum (3 ints): " << calculateSum(1, 2, 3) << "\n";
23    return 0;
24}

Name Mangling:

Under the hood, C++ compilers encode the parameter types into the assembly symbol name (e.g. _Z12calculateSumii), allowing the linker to differentiate overloaded functions.

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Pass-by-Const-Reference (const Type&) for Efficiency	Inline Functions and Intro to Recursion

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Inline Functions and Intro to Recursion

Default Arguments and Function Overloading

Beginner12 min read•Updated: 2026-10-22

Study Materials

🤹 Default Arguments and Function Overloading

Introduction

C++ enables polymorphism at compile time through function overloading (multiple functions sharing the same name with different parameter signatures) and default arguments.

⚙️ Default Arguments

Default arguments let callers omit parameters, substituting predefined defaults:

1#include <iostream>
2 
3// Note: Default arguments must be placed at the end of parameter list
4void printReceipt(double amount, double discountPercent = 0.0, double taxRate = 18.0) {
5    double discounted = amount - (amount * (discountPercent / 100.0));
6    double finalTotal = discounted + (discounted * (taxRate / 100.0));
7 
8    std::cout << "Base: ₹" << amount << " | Final Payable: ₹" << finalTotal << "\n";
9}
10 
11int main() {
12    printReceipt(1000);              // Uses default discount (0%) and tax (18%)
13    printReceipt(1000, 10.0);        // Uses 10% discount and default tax (18%)
14    printReceipt(1000, 10.0, 5.0);   // Overrides both discount and tax
15    return 0;
16}

🔄 Function Overloading

Functions can share an identical identifier as long as their parameter types or counts differ:

1#include <iostream>
2#include <string>
3 
4// Overload 1: Integers
5int calculateSum(int a, int b) {
6    return a + b;
7}
8 
9// Overload 2: Doubles
10double calculateSum(double a, double b) {
11    return a + b;
12}
13 
14// Overload 3: Three numbers
15int calculateSum(int a, int b, int c) {
16    return a + b + c;
17}
18 
19int main() {
20    std::cout << "Sum (int): " << calculateSum(10, 20) << "\n";
21    std::cout << "Sum (double): " << calculateSum(5.5, 4.2) << "\n";
22    std::cout << "Sum (3 ints): " << calculateSum(1, 2, 3) << "\n";
23    return 0;
24}

Name Mangling:

Under the hood, C++ compilers encode the parameter types into the assembly symbol name (e.g. _Z12calculateSumii), allowing the linker to differentiate overloaded functions.

Next Lesson

Inline Functions and Intro to Recursion

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

Related Lessons

Previous Lesson	Next Lesson
Pass-by-Const-Reference (const Type&) for Efficiency	Inline Functions and Intro to Recursion

Practice Quiz

Test your understanding of this lesson with 1 questions. Each question has one correct answer.

Previous Next