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tolower---translate characters to lower case

Synopsis 
#include <ctype.h>
int tolower(int c);
int _tolower(int c);
Description
tolower is a macro which converts upper-case characters to lower case, leaving all other characters unchanged. It is only defined when c is an integer in the range EOF to 255.

You can use a compiled subroutine instead of the macro definition by undefining this macro using `#undef tolower'.

_tolower performs the same conversion as tolower, but should only be used when c is known to be an uppercase character (A--Z).


Returns
tolower returns the lower-case equivalent of c when it is a character between A and Z, and c otherwise.

_tolower returns the lower-case equivalent of c when it is a character between A and Z. If c is not one of these characters, the behaviour of _tolower is undefined.


Portability
tolower is ANSI C. _tolower is not recommended for portable programs.

No supporting OS subroutines are required.


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