What is C++?
C++ is an
object-oriented programming language. It was developed by Bjarne Stroustrup
at AT&T belt laboratory in murry
hill, New Jersey, USA, in the early 1980s. Stroustrup, an admirer of simula67
and a strong supporter of C, wanted to combine the best of both the language
and create a more powerful language that could support object-oriented programming
features and still retain the power and elegance of c . The result was c++
therefore c++ is an extension of c with a major addition of the class construct features of
simula67. Since the class was a major addition to the original c language.
Important features add in c++ are -> Inheritance ,classes,function
overloading and operator overloading.
Applications
of C++
- C++ is a versatile language for handling very large programs.
- C++ allows us to create hierarchy-related objects, we can build special object-oriented libraries which can be used later by many programmers.
- While C++ is able o map the real-world problem properly, the C part of C++ gives the language the ability to get close to the machine-level details
- C++ programs are easily maintainable and expandable. when a new feature needs to be implemented it is very easy to add to the existing structure of an object
- It is expected that C++ will replace C as a general-purpose language in the near future.
BASIC CONCEPT OF OBJECT-ORIENTED PROGRAMMING
The concept
used extensively in object-oriented programming
These include:
- · Objects
- ·
Classes
- ·
Data
abstraction and encapsulation
- ·
Inheritance
- ·
Polymorphism
- ·
Dynamic
binding
- ·
Message
passing
Program features:
Like c, the
c++ program is a collection of functions. The above example contains only one function, main().
As
usual ,execution begins at main(). Every C++ program must have a main().c++ is
a free-form language. With few exceptions, the compiler ignores carriage returns and white spaces. Like c, the
c++ statements terminate with
semicolons.
Comments
C++
introduces a new comment symbol // (double slash ). Comment start with a
double slash, the double slash makes a single line as a comment in the program. The comment ensures the compiler that the comment is not a part of the program
Example : //
This is not a part of the program.
A simple C++ program
C++ is a programming language, but what
exactly is a program? A program is a set of instructions to execute in a sequence
way to give the desired output.
Let's do our first program: print ”hello word”
#include <iostream>
// Program prints out
"Hello, World" to screen
int main()
{ std::cout<<
"Hello, World."<<std::endl;
return 0;
}
The
hash (#) include is used when we want to include the header files from the
library in the compiler. The Turbo C compiler is used to execute code. In this
case, we are including a standard C++ library in our program. The file we want
to include is then specified inside the angle brackets <>. Here, we are
including a file called iostream.h. This file handles the input and output of
data to the console/screen.
After #include<iostream>
, the double slash // is called a comment. Comments in code are not executed by
the program. They are mainly to tell the person about the code or any block of code to easily understand by the coder. It is good
practice to comment your code so that when you look at code you wrote a year
ago, you will know what the code was doing then.
main()
is a function that tells the compiler from where the main program is started. We will cover functions shortly,
but the main function is the first function that is executed in a program, also
called the entry point. A function is used to perform a certain task. Here, the
printing of Hello, World is tasked to the main function. The contents that need
to be executed must be enclosed in the curly brackets of the function. The int is
a keyword from the set of 32 keywords and main is a function, int main() , suggests
that the function will return an integer. This is why we have returned 0 at the
end of the main function, suggesting that the program executed and the
program can terminate without errors.
When
we want to print out something to the console/screen, we use the std::cout
(console out) C++ command to send something to the screen. Whatever we want to
send out should precede and end with the output operator, <<.
<<std::endl is another C++ command, which specifies that it is the end
of the line and nothing else should be printed on this line afterward. We have
to use the prefix before the std:: code to tell C++ that we are using the
standard namespace with the namespace std. But why are namespaces necessary? We
need namespaces because anyone can declare a variable name with std. How would
the compiler differentiate between the two types of std? For this, we have
namespaces to differentiate between the two.
Note
that the two lines of code we have written in the main function have a
semicolon (;) at the end of each line. The semicolon tells the compiler that
this is the end of the instructions for that line of code so that the program
can stop reading when it gets to the semicolon and go to the next line of
instruction. Consequently, it is important to add a semicolon at the end of
each line of instruction as it is mandatory.
The
two lines of code we wrote before can be written in one line as follows:
std::cout<<
"Hello, World."<<std::endl; return 0;
Even
though it is written in a single line, for the compiler, there are two
instructions with both instructions ending with a semicolon. The first
instruction is to print out Hello, World to the console and the second
instruction is to terminate the program without any errors. It is a very common
mistake to forget semicolons and it happens to beginners as well as experienced
programmers every now and then. So it's good to keep this in mind, in case you
encounter your first compiler errors.
Some important terms in the C++
- ·
Program basics
- ·
Variables
- ·
Operators
- ·
Statements
- ·
Iteration
- ·
Functions
- ·
Arrays and pointers
- ·
Struct and Enum
- ·
Classes and inheritance
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