Category: C++

C++ Classes and Objects

C++ Classes/Objects

C++ is an object-oriented programming language.

Everything in C++ is associated with classes and objects, along with its attributes and methods. For example: in real life, a car is an object. The car has attributes, such as weight and color, and methods, such as drive and brake.

Attributes and methods are basically variables and functions that belongs to the class. These are often referred to as “class members”.

A class is a user-defined data type that we can use in our program, and it works as an object constructor, or a “blueprint” for creating objects.

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C++ OOP

C++ What is OOP?

OOP stands for Object-Oriented Programming.

Procedural programming is about writing procedures or functions that perform operations on the data, while object-oriented programming is about creating objects that contain both data and functions.

Object-oriented programming has several advantages over procedural programming:

  • OOP is faster and easier to execute
  • OOP provides a clear structure for the programs
  • OOP helps to keep the C++ code DRY “Don’t Repeat Yourself”, and makes the code easier to maintain, modify and debug
  • OOP makes it possible to create full reusable applications with less code and shorter development time

Tip: The “Don’t Repeat Yourself” (DRY) principle is about reducing the repetition of code. You should extract out the codes that are common for the application, and place them at a single place and reuse them instead of repeating it.

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C++ Recursion

Recursion

Recursion is the technique of making a function call itself. This technique provides a way to break complicated problems down into simple problems which are easier to solve.

Recursion may be a bit difficult to understand. The best way to figure out how it works is to experiment with it.

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C++ Variable Scope

Now that you understand how functions work, it is important to learn how variables act inside and outside of functions.

In C++, variables are only accessible inside the region they are created. This is called scope.

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C++ Function Overloading

Function Overloading

With function overloading, multiple functions can have the same name with different parameters:

Example

int myFunction(int x)
float myFunction(float x)
double myFunction(double x, double y)

Consider the following example, which have two functions that add numbers of different type : Continue reading C++ Function Overloading

C++ Function Examples

Real Life Example

To demonstrate a practical example of using functions, let’s create a program that converts a value from fahrenheit to celsius :

Example

// Function to convert Fahrenheit to Celsius
float toCelsius(float fahrenheit) {
  return (5.0 / 9.0) * (fahrenheit - 32.0);
}

int main() {
  // Set a fahrenheit value
  float f_value = 98.8;

  // Call the function with the fahrenheit value
  float result = toCelsius(f_value);

  // Print the fahrenheit value
  cout << "Fahrenheit: " << f_value << "\n";

  // Print the result
  cout << "Convert Fahrenheit to Celsius: " << result << "\n";

  return 0;
}

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C++ Pass Array to a Function

Pass Arrays as Function Parameters

You can also pass arrays to a function :

Example

void myFunction(int myNumbers[5]) {
  for (int i = 0; i < 5; i++) {
    cout << myNumbers[i] << "\n";
  }
}

int main() {
  int myNumbers[5] = {10, 20, 30, 40, 50};
  myFunction(myNumbers);
  return 0;
}

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C++ Functions – Pass By Reference

Pass By Reference

In the examples from the previous page, we used normal variables when we passed parameters to a function. You can also pass a reference to the function. This can be useful when you need to change the value of the arguments: Continue reading C++ Functions – Pass By Reference

C++ The Return Keyword

Return Values

The void keyword, used in the previous examples, indicates that the function should not return a value. If you want the function to return a value, you can use a data type (such as int, string, etc.) instead of void, and use the return keyword inside the function: Continue reading C++ The Return Keyword

C++ Multiple Parameters

Multiple Parameters

Inside the function, you can add as many parameters as you want:

Example

void myFunction(string fname, int age) {
  cout << fname << " Refsnes. " << age << " years old. \n";
}

int main() {
  myFunction("Liam", 3);
  myFunction("Jenny", 14);
  myFunction("Anja", 30);
  return 0;
}

// Liam Refsnes. 3 years old.
// Jenny Refsnes. 14 years old.
// Anja Refsnes. 30 years old.

Note that when you are working with multiple parameters, the function call must have the same number of arguments as there are parameters, and the arguments must be passed in the same order.

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