Table of Contents
CPPX
C++ compiler
To compile a C++ script, you can use g++ -o (new name) (uncompiled name).cpp
For example, to compile a script called script.cpp:
g++ -o script script.cpp
common file extensions
C++ file extensions:
.cpp
.CC
.cxx
C++ header file extensions
.hpp
.h
hxx
The recommended extensions are .cpp
and .hpp
- The selection of a file extensions usually comes down to preference or versions of software you're using
The output of the compiled code comes out as a .o
file
Preproccesed C++ Source Files have a .ii
file extension
Classes
A class in C++ is a user-defined type or data structure declared with any of the keywords class
, struct
, or union
- By default access to members of a C++ class declared with the keyword
class
is private. The private members are not accessible outside the class; they can be accessed only through member functions of the class - The public members form an interface to the class and are accessible outside the class.
For example:
// Define the class class MyClass { // Class members go here };
Member Functions
Member functions are the functions, which have their declaration inside the class definition and works on the data members of the class. The definition of member functions can be inside or outside the definition of class.
- if its defined outside the class, use the scope resolution
::
operator along with class name along with function name.
defined inside:
class Cube { public: int side; int getVolume() { return side*side*side; //returns volume of cube } };
defined outside:
class Cube { public: int side; int getVolume(); } int Cube :: getVolume() { return side*side*side; }
Constructor
A constructor in C++ is a special ‘MEMBER FUNCTION’ having the same name as that of its class which is used to initialize some valid values to the data members of an object. It is executed automatically whenever an object of a class is created.
default constructor
class Line { public: int size; Line() { size=30; } }; ///////////// int main() { //default constructor called when object is created Line l; }
parameter constructor
class ABC { private: int x,y; public: ABC () //constructor 1 with no arguments { x = y = 0; } ABC(int a) //constructor 2 with one argument { x = y = a; } ABC(int a,int b) //constructor 3 with two argument { x = a; y = b; } }; ///////////////// int main() { ABC cc1; //constructor 1 ABC cc2(10); //constructor 2 ABC cc3(10,20); //constructor 3 return 0: }
Destructor
A destructor is a member function that is invoked automatically when the object goes out of scope or is explicitly destroyed by a call to delete
or delete[]
. A destructor has the same name as the class and is preceded by a ~
. Example:….
- the destructor for class String is declared: ~String()
class String { public: String(const char* ch); // Declare the constructor ~String(); // Declare the destructor private: char* _text{nullptr}; }; // Define the destructor. String::~String() { // Deallocate the memory that was previously reserved for the string. delete[] _text; }
Member Data
A data member in C++ is a non-function member of a class (class, struct, or union).
class C { // In C++, this is a "data member". int x; };
Access Control
Access controls enable you to separate the public
interface of a class from the private
implementation details and the protected
members that are only for use by derived classes.
Access control helps prevent you from using objects in ways they weren't intended to be used. This protection is lost when you make explicit type conversions.
Public
Class members declared as public
can be used by any function.
For example:
class MyClass { public: int publicMember; };
Private
Class members declared as private
can be used only by member functions and friends (classes or functions) of the class.
For example:
class MyClass { private: int privateMember; };
Protected
Class members declared as protected
can be used by member functions and friends (classes or functions) of the class. Additionally, they can be used by classes derived from the class.
For example:
class MyClass { protected: int protectedMember; };
Objects
In C++, an object is created from a class.
class CLASSNAME { Public: int sumthinNumb; } ///////////////////////// int main() { CLASSNAME objname; objname.sumthinNumb = 12834589028390458; cout << objname.sumthinNUmb << "/n"; return 0; } }