HP Integrity NonStop H-Series - Manual (Page 241)

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©Copyright 1996 Rogue Wave Software
Overview
A new feature of the C++ Standard Library is an organized mechanism for describing the
characteristics of the fundamental types provided in the execution environment. In older C and
C++ libraries, these characteristics were often described by large collections of symbolic
constants. For example, the smallest representable value that could be maintained in a character
would be found in the constant named CHAR_MIN, while the similar constant for a short
would be known as SHRT_MIN, for a float FLT_MIN, and so on.
Two Mechanisms, One Purpose
The template class numeric_limits provides a new and uniform way of representing this
information for all numeric types. Instead of using a different symbolic name for each new data
type, the class defines a single static function, named min(), which returns the appropriate
values. Specializations of this class then provide the exact value for each supported type. The
smallest character value is in this fashion yielded as the result of invoking the function
numeric_limits::min(), while the smallest floating point value is found by invoking
numeric_limits::min(), and so on.
Solving this problem by using a template class not only greatly reduces the number of symbolic
names that need to be defined to describe the operating environment, but it also ensures
consistency between the descriptions of the various types.