CPP Basics

Overview of CPP Basics.

The function header describes the interface between a function and the function that calls it.

The list-initialization protects against narrowing.

Raw string use R"(...)".

Bit Fields in Structures

struct torgle_register
{
    unsigned int SN : 4;    // 4 bits for SN value
    unsigned int : 4;       // 4 bits unused
    bool goodIn : 1;        // valid input
    bool goodTorgle: 1;     // successful torgling
};

Prefixing Versus Postfixing

The user defines a prefix function that works by incrementing a value and then returning it. But the postfix version works by first stashing a copy of the value, incrementing the value, and then returning the stashed copy.Thus, for classes, the prefix version is a bit more efficient than the postfix version. In short, for built-in types, it most likely makes no difference which form you use. For user-defined types having user-defined increment and decrement operators, the prefix form is more efficient.

The comma operator is a sequence point. C++ states that the value of a comma expression is the value of the second part of the expression.

cin.get(ch) Versus cin.get()

A reference is rather like a const pointer; you have to initialize it when you create it, and when a reference pledges its allegiance to a particular variable, it sticks to its pledge.

Rvalue reference, that can refer to an rvalue. It’s declared using &&:

double && rref = std::sqrt(36.00);
double j = 15.0;
double && jref = 2.0* j + 18.5;
std::cout << rref << '\n';
std::cout << jref << '\n';

Storage Duration, Scope, and Linkage

The following are the most important OOP features:

• Abstraction
• Encapsulation and data hiding
• Polymorphism
• Inheritance
• Reusability of code

You can use only member functions to overload the following operators:

Conversion Function

To convert to type typeName, you use a conversion function in this form:

operator typeName();

Note the following points:

• The conversion function must be a class method.
• The conversion function must not specify a return type.
• The conversion function must have no arguments.

Special Member Functions

C++ automatically provides the following member functions:

• A default constructor if you define no constructors
• A default destructor if you don’t define one
• A copy constructor if you don’t define one
• An assignment operator if you don’t define one
• An address operator if you don’t define one
• move constructor
• move assignment operator

Virtual Function Mechanism

Using virtual functions has the following modest costs in memory and execution speed:

• Each object has its size increased by the amount needed to hold an address.
• For each class, the compiler creates a table (an array) of addresses of virtual functions.
• For each function call, there’s an extra step of going to a table to look up an address.

Member Function Properties

Here, operator op= represents compound-assignment operators such as operator+=, operator-=, operator*=, and operator/=.