Language concepts

The language concepts characterize types by their “shape” or by their categorization according to the C++ standard. The “shape” of a type is based on its spelling. For example, a pointer type has the shape T*, where T is any other type. Similarly, an array of bound N has the shape T[N].

The C++ language and standard library also define categories based on semantic properties of types. For example, the object types are all those types that can hold a value in memory, which is everything except void, function types, and reference types. A polymorphic type is one that has at least one virtual function.

The language concepts closely parallel type traits with similar names. We use the suffix _type to indicate that these are characterizations and not specifications of abstract interfaces. They are:

• Integral_type
• Signed_type
• Unsigned_type
• Floating_point_type
• Pointer_type
• Lvalue_reference_type
• Rvalue_reference_type
• Array_type