Review of static keyword uses In the lesson on file scope and the static keyword, you learned that static variables keep their values and are not destroyed even after they go out of scope. For example: #include <iostream> int generateID() { static int s_id{ 0 }; return ++s_id; } int …
In lesson , you learned that fundamental data types (int, double, char, etc…) can be made const via the const keyword, and that all const variables must be initialized at time of creation. In the case of const fundamental data types, initialization can be done through copy, direct, or uniform …
Defining member functions outside the class definition All of the classes that we have written so far have been simple enough that we have been able to implement the member functions directly inside the class definition itself. For example, here’s our ubiquitous Date class: class Date { private: int m_year; …
When you instantiate a new object, the object’s constructor is called implicitly. It’s not uncommon to have a class with multiple constructors that have overlapping functionality. Consider the following class: class Foo { public: Foo() { // code to do A } Foo(int value) { // code to do A …
One of the questions about classes that new object-oriented programmers often ask is, “When a member function is called, how does C++ keep track of which object it was called on?”. The answer is that C++ utilizes a hidden pointer named “this”! Let’s take a look at “this” in more …
A destructor is another special kind of class member function that is executed when an object of that class is destroyed. Whereas constructors are designed to initialize a class, destructors are designed to help clean up. When an object goes out of scope normally, or a dynamically allocated object is …
When all members of a class (or struct) are public, we can use to initialize the class (or struct) directly using list-initialization: class Foo { public: int m_x {}; int m_y {}; }; int main() { Foo foo { 6, 7 }; // list-initialization return 0; } However, as soon …
Why make member variables private? In the previous lesson, we mentioned that class member variables are typically made private. Developers who are learning about object-oriented programming often have a hard time understanding why you’d want to do this. To answer that question, let’s start with an analogy. In modern life, …
Consider the following struct: struct DateStruct // members are public by default { int month {}; // public by default, can be accessed by anyone int day {}; // public by default, can be accessed by anyone int year {}; // public by default, can be accessed by anyone }; …
While C++ provides a number of fundamental data types (e.g. char, int, long, float, double, etc…) that are often sufficient for solving relatively simple problems, it can be difficult to solve complex problems using just these types. One of C++’s more useful features is the ability to define your own …
