freebsd man page for tolower

TOLOWER(3)						   BSD Library Functions Manual 						TOLOWER(3)

NAME
     tolower -- upper case to lower case letter conversion

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <ctype.h>

     int
     tolower(int c);

DESCRIPTION
     The tolower() function converts an upper-case letter to the corresponding lower-case letter.  The argument must be representable as an
     unsigned char or the value of EOF.

RETURN VALUES
     If the argument is an upper-case letter, the tolower() function returns the corresponding lower-case letter if there is one; otherwise, the
     argument is returned unchanged.

COMPATIBILITY
     The 4.4BSD extension of accepting arguments outside of the range of the unsigned char type in locales with large character sets is considered
     obsolete and may not be supported in future releases.  The towlower() function should be used instead.

SEE ALSO
     ctype(3), islower(3), towlower(3)

STANDARDS
     The tolower() function conforms to ISO/IEC 9899:1990 (``ISO C90'').

BSD
								   July 25, 2010							       BSD