C++ LectuNSVAHDVQwyfkyuQWVHGWQUDKFEre-14.pptx

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LECTURE 14
Modern C++

Today’s Agenda
01
03 Differences with standard c++
What is Modern C++ ?
05
What is C++ 11 , C++ 14 and C++ 17?
New features of C++
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02
01
05

.
What Is Modern C++?
 C++ is one of the most widely used programming language in the world.
 It’s been around from the last 40 years and was initially much like C language
due to backward compatibility.
 But to meet modern computing requirements it was redesigned in the year
2011 and the name Modern C++ was given.

.
What Is Modern C++?
 After C++ 11, two newer versions of the standards have
been accepted:
. C++ 14: which is a bugfix to C++11.
. C++ 17: which adds some more new features to the language
 So now the term Modern C++ refers to C++11, C++14,
and C++17

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Little History Of C++11/14/17?
 C++11 is a version of the standard for the programming
language C++.
 It was approved by the International Organization for Standardization (ISO)
on 12th
August 2011, replacing classic C++, and superseded by C++14 on 18th
August 2014.
 Then on 1st
Dec 2017 , C++ 17 was released with some
new modules and features.

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Which Compiler Support C++17?
 All modern compilers except Turboc C++ 3.0 are now fully supporting C++ 17
standards .
 The most popular compilers are GCC C++, Clang C++, and Microsoft C++ and
following table lists their support for C++ 17:
Compiler C++17 Support
GCC8 Full Support For C++17
Clang C++ Implements all the features of C++17
Microsoft C++ Supports almost all of C++17

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Which Compiler We will Use?
 Since we are using Code Blocks IDE which has support for GCC compiler so we
will be using GCC.
 Moreover , since there is not much difference in C++14 and C++17 so any
version of Code blocks which supports them will work

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Modern C++ Features
 C++14/17 has lot of new concepts which were not present in classic C++.
 All these new features make Modern C++ programs type-safe and easier to
write, extend, and maintain.
These are listed on the next slide

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Modern C++ Features
New Topics
New concepts of header files Lambda Expressions
Namespaces Rvalue References
Automatic type declaration Smart Pointer,Unique Pointer,Shared Pointer
New syntaxes of initialization Static cast, Reinterpret cast,Dynamic cast
Deleted functions Exception Handling
Nullptr Standard Template Library
Delegating constructors
Override and final
The String Class

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What Is CodeBlock?
 Code::Blocks is a free, open-source cross-platform IDE (not a compiler) which
was designed to support C and C++ languages
 However now it also supports other languages, including Fortran and D.

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What Compiler Code Blocks Uses?
 Code::Blocks supports multiple compilers like:
• GCC,
• MinGW,
• Digital Mars,
• Microsoft Visual C++,
• Borland C++,
• LLVM Clang,
• Watcom,
• LCC and
• the Intel C++ compiler.

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Important Difference Between Standard
C++ and C++11/14/17
1. The names of all C++ header files do not contain .h extension
2. So <iostream.h> becomes <iostream> , <fstream.h> becomes <fstream> and so
on
3. For C language header files we still have the .h convention available but
recommendations are to use these header file names prefixed with the letter
‘c’ and dropping ‘ .h’.
4. So <math.h> becomes <cmath>, <stdlib.h> becomes <cstdlib> and so on

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C++ and C++11/14/17
5 All predefined object like cout , cin etc are now placed inside something called
namespace
6 The default namespace provided by c++ is called std
7 So instead of writing cout , the statement now becomes std::cout

.
C++ and C++11/14/17
#include <iostream>
int main()
{
std::cout<<"Welcome To c++ 14";
return 0;
}

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What Is A Namespace?
Before we discuss exactly what a namespace is, it is probably best to
consider a simple example of when and why we would need them.
Consider the following code:
#include <iostream>
int main()
{
int value;
value = 0;
double value;
value = 0.0;
std::cout<<value;
return 0;
}
Error Here!

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 In each scope, a name can only represent one entity. So, there cannot be two
variables with the same name in the same scope.
 Using namespaces, we can create two variables or functions having the same
name
Syntax:
namespace <some_name>
{
entities
}

.
namespace first
{
int val;
}
namespace second
{
double val;
}
int main()
{
first::val=10;
second::val=1.5;
return 0;
}

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Points To Remember
1. Namespace is a logical compartment used to avoid naming collisions.
2. Default namespace is global namespace and can access global data and
functions by proceeding (::) operator.

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Points To Remember
3. We can create our own namespace and anything declared within namespace
has scope limited to namespace.
4 Creation of namespace is similar to creation of class.

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Points To Remember
5. Namespace declarations can appear only at global scope
6. Namespace declarations don’t have access specifiers. (public or private)
7. No need to give semicolon after the closing brace of definition of namespace.

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The Namespace “STD”
 The built in C++ library routines are kept in the standard namespace called std
 That includes stuff like cout, cin, string, vector etc.
 Since they are in namespace std so we need to apply the prefix std:: with each
one of them.
 Thus cout becomes std::cout , cin becomes std::cin and so on

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The Namespace “STD”
#include <iostream>
int main()
{
int a,b,c;
std::cout<<“Enter 2 int”<<std::endl;
std::cin>>a>>b;
c=a+b;
std::cout<<“Nos are “<<a<<“ and “<<b<<std::endl;
std::cout<<“Their sum is “<<c;
return 0;
}

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Avoiding “STD”
 The keyword using is used to introduce a name from a namespace into the
current declarative region.
 So using namespace std means that we are going to use classes or functions
(if any) from "std" namespace
 Thus we don't have to explicitly call the namespace to access them.

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Modified Version
#include <iostream>
using namespace std;
int main()
{
int a,b,c;
cout<<“Enter 2 int”<<endl;
cin>>a>>b;
c=a+b;
cout<<“Nos are “<<a<<“ and “<<b<<endl;
cout<<“Their sum is “<<c;
return 0;
}

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New Data Types Added
 int : upgraded to 4 bytes
 bool : a special type of 1 byte in size for storing true/ false.
 wchar_t: a special data type for storing 2 bytes of characters
 long long : a new data type of integer family supporting size of 8bytes.

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The “Auto” Keyword
• In Modern C++, the compiler can automatically determine the data type of a
variable at the point of declaration using it’s initialization expression:
• So,
int x = 4;
• can now be replaced with
auto x = 4;
• This is called automatic type deduction.

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• Also we can write
char *p=“Bhopal”;
as
auto p= “Bhopal”;
• This also applies to pointers of class type.
• So ,
Box *p = new Box;
can also be written as
auto p= new Box;

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• The auto keyword can also automatically detect a function’s return type
• For example:
auto add(int x, int y)
{
return x + y;
}
• Since x + y evaluates to an integer, the compiler will detect this function should
have a return type of int.

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New Ways Of Initialization
• Modern C++,supports three basic ways to initialize a variable:
• Copy initialization
• Direct initialization
• Uniform initialization

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• Copy initialization : is done using assignment operator
int n = 5; // copy initialization
• Direct initialization : is done by using parenthesis.
int n(5); // direct initialization

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• Uniform initialization : is done using curly braces
int n { 5 }; // uniform initialization
If we leave the braces blank then compiler initializes
the variable to 0.
For Example
int n{ };
cout<<n ; // will display 0

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In Class Initialization
• Modern C++ allows us to initialize data members at the point of declaration and this
is called In-Class Initialization
class Circle
{
int radius=10; // OK , from C++ 14 onwards
.
.
};
But , remember if we do not initialize them , their default
value will still be garbage

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Range Based For Loop
• Modern C++ provides us an easy way to traverse an array called “Range Based For
Loop”.
• Syntax:
for(<data type> <var_name>: <array_name>)
{
//loop body
}
• Example:
int arr[ ]={10,20,30,40};
for(int x:arr)
cout<<x<<endl;

End of Lecture 14
Thank you
For any queries mail us @: scalive4u@gmail.com
Call us @ : 0755-4271659, 7879165533

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