C++ High Performance

Type trait categories

There are two categories of type traits:

• Type traits that return information about a type as a boolean or an integer value
• Type traits that return a new type

The first category returns true or false depending on the input and ends with _v (short for value).

The _v postfix has been added in C++17. If your STL implementation does not provide _v postfixes for type traits, then you can use the older version, std::is_floating_point<float>::value. In other words, remove the _v extension and add ::value at the end.

Here are some examples of compile-time type checking using type traits:

auto same_type = std::is_same_v<uint8_t, unsigned char>; 
auto flt = 0.3f; 
auto is_float_or_double = std::is_floating_point_v<decltype(flt)>; ...