Classes and Types

Classes

Copy constructors (new)

A copy constructor is a standard class constructor, but it’s only argument is a class object itself. It essentially creates a new object with the same properties.

Copy assignments (overwrite)

Copy assignments work the same as copy constructors, but they overwrite an existing object.

Rule of three / five / zero

The rule of three states that every class you create should have:

• A destructor (for de-allocating)
• A copy constructor (for duplicating to a new object)
• A copy assignment constructor (for duplicating to an existing object)

The rule of five states that every class you create should have:

• A destructor (for de-allocating)
• A copy constructor (for duplicating to a new object)
• A copy assignment constructor (for duplicating to an existing object)
• A move constructor (for moving to a new object)
• A move assignment constructor (for moving to an existing object)

The rule of zero states that every class you create should have:

None of these, because you can use memory safe datatypes like STD vectors, strings, unique_ptr’s, etc. This way, memory allocation happens automatically.

Access

Access modifiers decide if other parts of your code have access to variables and functions in a class.

C++ has private, public, and protected just [[School/Year 1/P2/Software-development/Object Oriented Programming#Encapsulation|like C#]], but c++ also has something else: a friend modifier.
Friend tells the program that exceptions for certain classes are made, which give them access to private/protected methods and variables.

Structs

A struct, or structure, is a datatype that can hold multiple variables under a single variable name. Its handy to group certain variables together. The biggest difference between a class and a struct is that struct members are public by default (and a class’s deconstructor is automatically called)

Typedef

A typedef is a way to give an alias to a variable. It doesn’t change the type, but gives it a shorter way to type it.

While using structs, you always need to explicitly type struct before using the variable. This can be fixed by using typedefs.

You can also use using in modern c++.

Enums

An enum, or enumeration, is a self defined type that holds a list of symbolic names which all have a (explicit or implicit) numerical value. It can be used for things like a list of seasons, days in a week, etc.. enums work great with switches.

Switch

A switch is a keyword that evaluates an expression and then runs a defined (switch)case.

switch (text)
{
	case "string1":
		//do things
		break;
	case "string2":
		//do things
		break;
	case "string3":
		//do things
		break;
}

Not adding a break at the end of the case will cause the execution to “fall-trough“ the next case without evaluating it.