CPP Tutorials

Compile Time Polymorphism in C++: An Easy Guide.

Introduction to Polymorphism in C++

Welcome to the world of Polymorphism in C++! Polymorphism is a key concept in OOP, enabling different objects to be treated as one parent type. In simple terms, it lets us use a common interface to work with various object types. In C++, we achieve this magic through virtual functions. In this article, we’ll explore why we need polymorphism, what it is, and how we can use it to write more flexible and efficient code. So get ready to discover the power of polymorphism and how it enhances the beauty of object-oriented programming! Let’s begin this exciting journey!

Understanding Compile Time Polymorphism

Compile-time polymorphism, also called static or early binding, is like solving a puzzle before you start playing. It means figuring out things in advance during the preparation phase. In C++, when we use compile-time polymorphism, the decisions about which functions to call are made during the early stages of writing the code, even before the program runs.

It’s like planning and arranging things on the table before starting to play with them. This ensures that everything is ready and well-organized when the game begins, making the program run smoothly and efficiently.


In compile-time polymorphism, decisions about which functions to call are made before the program runs, during the preparation phase. In C++, this is achieved through function overloading and operator overloading. Function overloading allows us to have multiple functions with the same name but different parameter lists and the right function is selected during the code compilation.

Similarly, operator overloading allows us to give special meanings to operators like ‘+’, ‘-‘, ‘<<‘, etc., when used with our custom objects. This way, C++ knows which function or operation to perform even before the program starts running, making it more efficient.


Compile-time polymorphism makes the code faster because it decides which function to use before the program runs. This way, there is less work to do during the actual execution, which reduces the time it takes to run the program.

It’s like knowing the best way to do something before you start doing it, so you can do it quickly and efficiently. This is why compile-time polymorphism is a great feature in C++ that helps improve the performance of your programs.

Function Overloading in C++

Function overloading is a concept in C++ that allows you to define multiple functions with the same name but different parameters. This means you can have several functions with the same name in a program, as long as their parameter lists are distinct.

The main idea behind function overloading is to provide a more intuitive and flexible way to call functions, making the code more readable and reducing the need for creating separate function names for slightly different operations.

Here are some key points about function overloading:

Parameter Types and/or Number of Parameters: Function overloading is based on differences in parameter types and/or the number of parameters in the function. This allows you to use the same function name for similar tasks that involve different data types or different amounts of information.

Return Type Doesn’t Matter: The return type of the overloaded functions can be the same or different. The compiler differentiates between overloaded functions based only on their parameter lists.

Example Syntax:

// Overloaded functions to calculate the area
double calculateArea(double radius) {
    return 3.14 * radius * radius;

double calculateArea(double length, double width) {
    return length * width;

Example Usage:

#include <iostream>
using namespace std;

const double PI = 3.14159265;

// Function to calculate the area of a circle given the radius
double calculateArea(double radius) {
    return PI * radius * radius;

// Function to calculate the area of a rectangle given the length and width
double calculateArea(double length, double width) {
    return length * width;

int main() {
    double circleArea = calculateArea(5.0);           // Calls the first function
    double rectangleArea = calculateArea(4.0, 6.0);   // Calls the second function

    cout << "Circle Area: " << circleArea << endl;
    cout << "Rectangle Area: " << rectangleArea << endl;

    return 0;


Circle Area: 78.5398
Rectangle Area: 24


  • Function Overloading: Two functions named ‘calculateArea‘ are declared and defined, each with a different set of parameters.
  • Circle Area Calculation: The first function takes a single double argument (radius) and calculates the area of a circle using the formula ( \pi \times \text{radius}^2 ).
  • Rectangle Area Calculation: The second function takes two double arguments (length and width) and calculates the area of a rectangle using the formula ( \text{length} \times \text{width} ).
  • Compile-Time Polymorphism: Based on the number of arguments passed to ‘calculateArea‘, the appropriate version of the function is called at compile time.
  • Ease of Use: By overloading the function, different geometrical shapes can be handled using the same function name, making the code more intuitive and easy to maintain.

Operator overloading in C++

Operator overloading is a powerful feature in C++ that allows you to redefine how certain operators work for your custom data types or classes. This means you can make operators like +, -, *, /, etc., work not only with built-in data types like integers and floats but also with your own user-defined classes. This helps in writing more intuitive and expressive code.

Let’s break down how operator overloading works:

  • Basic Idea: In C++, you can define your own custom behavior for operators when they are used with your class objects. This process is known as operator overloading.
  • Syntax: To overload an operator, you define a function with the operator keyword followed by the operator symbol. For example, to overload the + operator, you would define a function like this: ReturnType operator+(const YourClass& obj). The ReturnType should be the type of the result after the operation.
  • Example: Let’s say you have a Complex class to work with complex numbers. You can overload the + operator to add two complex numbers more intuitively. Here’s how the code might look:
#include <iostream>
using namespace std;

class Complex {
    double real, imag;

    Complex(double r, double i) : real(r), imag(i) {}

    Complex operator+(const Complex& other) {
        return Complex(real + other.real, imag + other.imag);

    friend ostream& operator<<(ostream& out, const Complex& c);

ostream& operator<<(ostream& out, const Complex& c) {
    out << c.real;
    if (c.imag >= 0) out << " + ";
    out << c.imag << "i";
    return out;

int main() {
    Complex num1(3.0, 4.0);
    Complex num2(1.5, 2.5);
    Complex sum = num1 + num2;

    cout << "Number 1: " << num1 << endl;
    cout << "Number 2: " << num2 << endl;
    cout << "Sum: " << sum << endl;

    return 0;


Number 1: 3 + 4i
Number 2: 1.5 + 2.5i
Sum: 4.5 + 6.5i


  • Complex Number Class: The ‘Complex‘ class is defined to represent a complex number with real and imaginary parts. It includes a constructor to initialize these parts and an overloaded addition operator for adding complex numbers.
  • Overloaded Addition Operator: The operator+ function is defined inside the Complex class to add two complex numbers together. It adds the real parts and the imaginary parts separately and returns a new Complex object.
  • Overloaded Insertion Operator: The operator<< function is defined as a friend of the Complex class to enable printing complex numbers using the << operator. It prints the real and imaginary parts in a readable format.
  • Creating and Adding Complex Numbers: In the main function, two Complex objects, num1 and num2, are created and added together using the overloaded + operator. The result is stored in a new Complex object called sum.

Understand By Detailed Diagram

Below is a detailed diagram showing the use of Compile Time Polymorphism in C++. Compile Time Polymorphism is achieved through function overloading in C++, where functions with the same name but different parameters are defined within a class.

  • Class Definition: Define a class with multiple functions having the same name but different parameters.
  • Function Overloading: Implement function overloading inside the class.
  • Main Function: Create a main function to instantiate the class and call the overloaded functions.
  • Compile: Compile the code using a C++ compiler to check for any errors.
  • Execution: Execute the compiled code to see the output of the overloaded functions.
  • Result: The correct function is called based on the parameters passed, demonstrating compile-time polymorphism.
Compile Time Polymorphism in C++

Real-life Example of Compile Time Polymorphism

Compile-time polymorphism is a concept in C++ that might sound complicated, but we can relate it to a real-life example to make it more approachable.

Compile-time polymorphism (also known as static polymorphism) in C++ is typically achieved using function overloading or operator overloading. It allows functions to perform differently based on the parameters that are passed to them.

Real-life Example

Imagine you’re in a kitchen, and you have a blender. This blender has different blades and settings to blend various items.

  1. With Fruit: You can use it to blend fruits to make a smoothie.
  2. With Ice: You can also use it to crush ice.
  3. With Vegetables: You can use it to puree vegetables for soup.

So, the same blender behaves differently based on what you put into it. It’s the same device (or function), but it performs differently depending on the input (or parameters).

C++ Example

This real-life example can be translated into C++ using function overloading, where we define multiple functions with the same name but with different parameters. Here’s a simple example:

#include <iostream>
using namespace std;

void blend(string ingredient) {
    cout << "Blending " << ingredient << " to make a smoothie.\n";

void blend(string ingredient, string texture) {
    cout << "Blending " << ingredient << " to make a " << texture << ".\n";

int main() {
    blend("fruits");                   // Call for blending fruits
    blend("vegetables", "puree");      // Call for blending vegetables into a puree
    blend("ice", "crushed ice");       // Call for crushing ice
    return 0;


Blending fruits to make a smoothie.
Blending vegetables to make a puree.
Blending ice to make crushed ice.

Just like the blender in the kitchen, the ‘blend‘ function in the C++ code behaves differently based on its inputs. This is a simple illustration of how compile-time polymorphism can be used in C++, and it shows how a real-world concept can be mapped into programming.

Examples of Compile Time Polymorphism

Let’s look at some examples of compile-time polymorphism in C++.

Example 1

Function overloading example:

#include <iostream>
using namespace std;

void display(int var) {
    cout << "Integer number: " << var << endl;
void display(double var) {
    cout << "Double number: " << var << endl;
void display(char* var) {
    cout << "String: " << var << endl;

int main() {
    return 0;


Integer number: 12
Double number: 7.9
String: Codinginterviewpro

In this example, the function ‘display()‘ is overloaded with different parameter types. The correct function to execute is determined by the argument passed.

Example 2

Operator overloading example:

#include <iostream>
using namespace std;

class Complex {
    int real, imag;
    Complex(int r = 0, int i =0) {real = r; imag = i;}
    Complex operator + (Complex const &obj) {
        Complex res;
        res.real = real + obj.real;
        res.imag = imag + obj.imag;
        return res;
    void print() { cout << real << " + i" << imag << endl; }

int main() {
    Complex c1(10, 5), c2(2, 4);
    Complex c3 = c1 + c2;


12 + i9

In this example, the ‘+’ operator is overloaded to add two Complex objects.

Pros and Cons of Compile Time Polymorphism

Efficient ExecutionRequires More Code
Resolved at Compile TimeLimited Flexibility
No Runtime OverheadMore Complexity to Understand and Maintain
Early Error DetectionDifficult to Change Behavior at Runtime
Improved Code ReadabilityLimited Dynamic Behavior
Pros and Cons of Compile Time Polymorphism

Key Takeaways

  • Compile-Time Polymorphism: In C++, compile-time polymorphism enables functions to behave differently based on their inputs during the compilation phase.
  • Function Overloading: This feature is achieved through function overloading, where multiple functions with the same name but different parameter types can exist. The compiler selects the appropriate function based on the provided arguments.
  • Operator Overloading: Along with functions, compile-time polymorphism involves operator overloading. This allows custom behavior for operators based on the data types they work with.
  • Readable and Efficient Code: Using compile-time polymorphism makes code more readable by providing clear function names, even for similar operations on different data types. This also results in more efficient code execution as the proper function is resolved during compilation.
  • Flexibility and Organization: Compile-time polymorphism enhances code flexibility, allowing the same function or operator to work seamlessly with various data types. This feature contributes to creating well-organized and adaptable programs.


Understanding compile-time polymorphism is crucial for writing efficient C++ code. It allows for code reusability and flexibility, making your code more organized and manageable. So keep practicing, and you’ll soon master this essential concept!


  • What is compile-time polymorphism in C++? Compile-time polymorphism, also known as static or early binding, is a type of polymorphism that is resolved at compile time. It is achieved through function overloading and operator overloading.
  • What is function overloading in C++? Function overloading is a feature in C++ where two or more functions can have the same name but different parameters. The correct function to be called is determined by the arguments passed.
  • What is operator overloading in C++? Operator overloading allows operators to have user-defined meanings on user-defined types (classes). It allows the same operator to have different meanings depending on its usage.
  • What are the benefits of compile-time polymorphism? Compile-time polymorphism improves code efficiency as the decision of which function to execute is made at compile time, reducing runtime overhead. It also enhances code readability and scalability.
  • Can compile-time polymorphism leads to problems? Yes, overloading can lead to confusion when maintaining code if not used carefully. It can also lead to unexpected results if the different functions are not properly handled.

Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button
Becoming a Full Stack Developer in 2023 How to Become a Software Engineer in 2023

Adblock Detected

Please consider supporting us by disabling your ad blocker!