what does :: mean and why its used

[gs8]

Write your question here.
what does :: mean and why its used like in string::size_type first, list<string>:: iterator i etc.

[coder777]

it's the scope operator. That means for string::size_type you will find size_type within the class (or base class) of string, like so:

class string : ...
{
...
  ... size_type
...
};

The same applies to iterator

Read this:

http://en.wikipedia.org/wiki/Scope_resolution_operator