what is variable?

Answer 1

It's an entity wich has a type and an identifier ( a name ) and stores a value. That variable also has an address.

The simplest way of declaring it is:
type name = expressionWichReturnsAnObjectOfTypetypeOrSimilar;
or
type identifier; if you dont want to initialize it to a value.
Here you are creating a variable "name" with type "type" and initialize it to the value of that expression.
Then you use it writing the identifier.

Answer 2

A variable stores a value. There are some. variable types, depending on what the variable stores. The basic variable types are:

-int ( integer )
- long ( or long long ) ( bigger integer )
- char ( a single character )
- string ( one or more characters ) ( it can be NULL )

eg:
int integer = 8;
long long a = 3000000000;
char letter = 'c';
string nickname = "nickname here";