Question

This is the statement from ISO C++ Standard 14.6.2.1: Dependent types :

A type is dependent if it is
— a template parameter,#1
— a qualified-id with a nested-name-specifier which contains a class-name
   that names a dependent type or whose unqualified-id names a dependent type,#2
— a cv-qualified type where the cv-unqualified type is dependent, #3
— a compound type constructed from any dependent type,#4
— an array type constructed from any dependent type or whose size is specified
    by a constant expression that is value-dependent, #5
— a template-id in which either the template name is a template parameter
   or any of the template arguments is a dependent type or an expression 
   that is type-dependent or value-dependent.#6 

I am unable to understand the last two points?

Can any one give examples for these statements(especially for last #5,#6 )?

Answer 1

Working from 1) a type is dependent if it is a template parameter:

template <typename T, int N, template <typename> class My_Template>
struct X
{

5 — an array type constructed from any dependent type or whose size is specified by a constant expression that is value-dependent,

    T a[5];        // array of dependent type
    int b[N];      // value-dependent size

6 — a template-id in which either the template name is a template parameter
or any of the template arguments is a dependent type or an expression
that is type-dependent or value-dependent.

    My_Template<int> c;           // template parameter
    Some_Template<T> d;           // template argument is dependent
    Another_Template<sizeof c> e; // type-dependent expression
    Another_Template<N> f;        // value-dependent expression
};