PROJECT: C Plus Plus (CPP0)

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

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

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 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;
}

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:
}

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;
}

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 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.

Class members declared as public can be used by any function.

For example:

class MyClass {
public:
    int publicMember;
};

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;
};

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;
};

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;
}
}