ANSI C++ New Features

ANSI C++ New Features

The ISO / ANSI C++ include several new features to the original C++ specifications. Some of the new features are added to provide better control in certain situations while others are included to provide convenience to C++ programmers. It is to be noted that it is technically possible to write a full C++ program without the use of any new features. In this chapter you will learn about some of the important C++ features which are newly introduced with C++ language.

What are the new C++ features?

Some of the new C++ features are:

• New Data type:
  • bool
  • wchat_t
• Operator keywords
• New Headers
• Newly introduced operators
  • const_cast
  • static_cast
  • dynamic_cast
  • reinterpret_cast
  • typeid
• Namespace scope
• Class implementation
  • Explicit constructors
  • Mutable members

New ANSI C++ data types

Two new data types have been added to the ANSI C++ for enhancing the range of data type. These are:

bool

This data type has the capability to hold boolean values i.e. wither true or false. The values true and false have been added to the set of C++ keywords. The bool type variable can be declared as follows:

bool g1;
g1=true;
bool ks = false;

wchar_t

This type of data type has been defined by ANSI C++ for holding 16 bit wide character. These are used to represent a character set of languages that have more than 255 characters. This concept is important if programmers write programs for international distribution having different international languages. Wide_character literals begin with the character / letter L and is written as:

L ‘ab’

New Operators

You might have earlier used the type cast which is used to change the type of variable dynamically. It is used to convert a value from one type to another. This concept is necessary in cases where the automatic conversion is not possible within a program. We need to use these following forms of casting:

double y = double (m);            // Type casing in C++

double g = (double)n;              //Type casting in C

Although these casts still works, ANSI C++ has added new type cast operators. These are:

• Static casts
• Dynamic casts
• Reinterpret casts
• Constant casts

This new concept also added another operator known as typeid for verifying the type of unknown objects.

Class Implementation in C++

New ANSI C++ has 2 unusual keywords, explicit and mutable, generally used with class members. The explicit keyword is applied in C++ for declaring class constructors to be explicit constructors. As we know that any constructor that is called with one argument performs implicit conversion in which the type received by the constructor is converted to an object of the class in which the constructor is defined.

Example:

class G
{
  int x;
  public:
  explicit G(int i)
 {
   x=i;
 }
. . . . . . . .
};

In this case, the objects of G class can be created using only the following form:

G g_obj(100(;

The automatic conversion form:

G g_obj2 = 100;

The mutable keyword also plays a major role in C++. Class objects or member function may be declared as const, thus making their member data not modifiable. But in programming, there may arise some situations where programmers may want to create a constant object but would likely to modify particular data item. In such situations data item may be declared as mutable.

Example:

mutable int s;

Although a function that contains k is declared const, the value of k may be modified. This is the special characteristics of mutable keyword.

Namespace Scope

Programmers can define their own namespace within a program. The syntax of defining a namespace is similar to the syntax of defining class. The general form of namespace is:

Syntax:

namespace namespace_name
{
//Declaration of variables, functions and classes
}

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