21.2 Fundamental Datatypes

The C++ Standard Library describes a specific type by providing a specialization of the numeric_limits template for the type. Static member functions and static constant data members then provide information specific to the type. The C++ Standard Library includes descriptions of the fundamental datatypes given in Table 21.

Table 21: Fundamental datatypes of the C++ Standard Library 

Certain implementations may also provide information on other datatypes. Whether or not an implementation is described can be discovered using the static data member is_specialized. For example, the following is legal, and will indicate that the string datatype is not described by this mechanism.

std::cout << "are strings described " <<
   std::numeric_limits<string>::is_specialized << std::endl;

For datatypes that do not have a specialization, the values yielded by the functions and data members in numeric_limits are generally zero or false.