Differences between std::is_integer and std::is_integral?

Question

C++11 provides two type trait template classes: std::is_integer and std::is_integral. However, I cannot tell the differences between them.

Answer 1

There is no type T that has different results for std::is_integral::value and std::numeric_limits::is_integer. To quote the draft Standard:

3.9.1 Fundamental types [basic.fundamental]

7 Types bool, char, char16_t, char32_t, wchar_t, and the signed and unsigned integer types are collectively called integral types. A synonym for integral type is integer type.[...]

18.3.2.4 numeric_limits members [numeric.limits.members]

static constexpr bool is_integer;

17 True if the type is integer.

20.9.4.1 Primary type categories [meta.unary.cat] (table 47)

template  struct is_integral;

T is an integral type (3.9.1)