How can you determine the maximum value that a numeric variable can hold?

The easiest way to find out how large or small a number that a particular type can hold is to use the values defined in the ANSI standard header file limits.h. This file contains many useful constants defining the values that can be held by various types, including these:

For integral types, on a machine that uses two’s complement arithmetic (which is just about any machine you’re likely to use), a signed type can hold numbers from –2^{(number of bits -1)} to +2^{(number of bits -1)} – 1. An unsigned type can hold values from 0 to +2^{(number of bits)} – 1. For instance, a 16-bit signed integer can hold numbers from –2¹⁵(–32768) to +2¹⁵ – 1 (32767).