The limits.h header determines various properties of the various variable types. The macros defined in this header, limits the values of various variable types like char, int and long.
These limits specify that a variable cannot store any value beyond these limits, for example an unsigned character can store up to a maximum value of 255.
Library Macros
The following values are implementation-specific and defined with the #define directive, but these values may not be any lower than what is given here.