Concept of enumeration in C++

You have often heard about "enumeration" in C++.Today I will explain this concept with the help of articles taken from different websites.

Definition of enumeration

Enum(enumeration) is a user-defined type consisting of a set of enumerators( enumerator --- named integer constant).

The idea behind enumerated types is to create new data types that can take on only a restricted range of values. Moreover, these values are all expressed as constants rather than magic numbers--in fact, there should be no need to know the underlying values.

Declaration of enumeration

The enum is declared as:

enum enum-type-name { enum-list } enum-variable;

In this form, enum-type-name is optional. However, if you want to use enum type in several places, it is better to use another way of enum declaration:

enum enum-type-name { enum-list };

//... (and somewhere below)

enum enum-type-name enum-variable;

Of course, in the second case enum-type-name cannon be omitted.

An example is given below which will show you how to declare enumeration in C++.
enum e_acomany
{
Audi,
BMW, 
Cadillac, 
 Ford,
 Jaguar, 
 Lexus, 
 Maybach, 
 RollsRoyce, 
 Saab
};

Below is a sample code that will help you to undersatnd this concept.

Source code

#include<iostream>

using namespace std;

enum colours{blue,red};

int main( )

{

colours c;

c=blue;

cout<<"Blue is at number:"<<c<<endl;

c=red;

cout<<"Red is at number:"<<c<<endl;

return 0;

}

Output

Blue is at number:0

Red is at number:1

Credits

For this blog,I have taken help from the following websites:

www.programiz.com

en.cppreference.com

www.anyexample.com

Funniest side of C++ functions

Do you agree?

C++ functions

Importance of pointers in C++

Today I found a very helpful article on "programmers.stackexchange.com" regarding the importance of pointers in C++.This article was written by David Thornley.So,I decided to share it with all my readers.

Importance of pointers in C++

Pointers are necessary for dynamic memory location, many data structures, and efficient handling of large amounts of data. Without pointers, you'd have to allocate all the program data globally or in functions or the equivalent, and you'd have no recourse if the amount of data grew beyond what you had originally allowed for. I hesitate to use absolutes here, but as far as I know all modern computer languages have pointers in some form or other.

In most languages that use pointers, there are certain sorts of references that are pointers, and perhaps certain sorts of references that aren't, and there is no further notational difference. A Lisp cons cell is a pair of pointers, although a fixnum is not a pointer. In Java, the variable used for the instance of a class is a pointer, but an int isn't. The language syntax doesn't reflect that.

C is unusual in that pointers are optional, explicit, and allow explicit pointer arithmetic. It is perfectly possible to write struct foo bar; struct foo * baz;, and once you've allocated memory for bazyou can use both bar and baz to represent struct foos. Since pointers are optional, it is useful to have notational differences. (It's essential in C++ for smart pointers, as given boost::shared_ptr<foo> bar;, bar.reset() has one meaning and bar->reset() is likely to have a much different one.)

(Actually, explicit pointers were often used in other languages when C was originally being developed, such as ^ in Pascal. C is an older language than most in common use today, and it shows.)

One of C's design goals was to write Unix in, and therefore it needed to handle memory locations in a detailed manner. (C is actually one of a family of system implementation languages common when it was being designed, another example being Cybol for Control Data computers. C is the one that became a big hit.) Therefore, it is possible to manipulate C pointers directly, assigning memory addresses and calculating new ones. This also led to some design decisions in C. C arrays are based heavily on pointer arithmetic, and indeed an array decays into a pointer in very many situations. Passing variables to C functions by reference is done by pointer. There was no strong need for arrays and passing variables by reference in the form that other contemporary languages had, so C didn't get those.

So, the answer is that, in most languages nowadays, you use pointers constantly without being reminded of the fact. In C, and to a lesser extent C++, you use pointers either to do low-level things, or as accomplish higher-level things that there's no special notation for.

Real programmer

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Pointer Declaration in C++

Pointer Declaration

As I have discussed in the previous blog that a pointer is a variable whose value is the address of another variable.Remember that the declaring a pointer is same as declaring a simple variable.An asterisk "*" is used in the declaration that indicates that the variable is a pointer variable.

Syntax

The syntax of declaring a pointer is as follows:

DataType *var;

Example

int *p;

Now,I will demonstrate this concept by a simple program.

Source code

#include<iostream>

#include<conio.h>

using namespace std;

void main( )

{

int n;

int *ptr; // it indicates that "ptr" is a pointer

cout<<"Enter an integer";

cin>>n;

ptr=&n;

cout<<"The value of n:"<<n<<endl;

cout<<"The address of n:"<<ptr<<endl;

getch( );

}

Output

Evolution of C

Have a look at the evolution of C#,lol !!!!!!

Evolution of C