Give an example for the use of volatile keyword in c++ ?  

A variable provides us with named storage that our programs can manipulate. Each variable in C++ has a specific type, which determines the size and layout of the variable's memory the range of values that can be stored within that memory and the set of operations that can be applied to the variable.

The name of a variable can be composed of letters, digits, and the underscore character. It must begin with either a letter or an underscore. Upper and lowercase letters are distinct because C++ is case-sensitive −

Basic types of variables:

1. bool

Stores either value true or false.

2. char

Typically a single octet (one byte). This is an integer type.

3. int

The most natural size of an integer for the machine.

4. float

A single-precision floating point value.

5. double

A double-precision floating point value.

6. void

Represents the absence of type.

7. wchar_t

A wide character type.

Friends can be either functions or other classes. The class grants friends unlimited access privileges.

* The declaration of the function should be preceded by the keyword 'friend'.
* The function definition will not use the keyword or the scope operator '::'.

Thus, a friend function is an ordinary function or a member of another class.

Class can have a public method for specific data type conversions.
for example:
class B
{
double value;
public  B(int i )
operator double()
{
return value;
}
};
B BObject;
double i = BObject; // assigning object to variable i of type double.
now conversion operator gets called to assign the value.

It is advisable to use container classes of the STL so that you don’t have to go through the pain of writing the entire code for handling collisions, making sure its working well, testing it repeatedly with an overhead of time consumption.

Suppose you have some data that has values associated with strings and its fields consist of grades> in this situation you can directly use hash table instead of having it created by yourself.

A class is said to be a container class which is utilized for the purpose of holding objects in memory or persistent media. A generic class plays a role of generic holder. A container class is a good blend of predefined behavior and an interface that is well known. The purpose of container class is to hide the topology for the purpose of objects list maintenance in memory. A container class is known as heterogeneous container, when it contains a set of different objects. A container class is known as homogeneous container when it contains a set of similar objects.