tolower, tolower_l - transliterate upper-case characters to lower-case
#include <ctype.h> int tolower(int c); int tolower_l(int, locale_t locale);
The tolower() and tolower_l() functions have as a domain a type int, the value of which is representable as an unsigned char or the value of EOF. If the argument has any other value, the argument is returned unchanged. If the argument of tolower() or tolower_l() represents an upper-case letter, and there exists a corresponding lower-case letter as defined by character type information in the current or in the locale represented by locale, respectively (category LC_CTYPE), the result is the corresponding lower-case letter. All other arguments in the domain are returned unchanged.
The behavior is undefined if the locale argument to tolower_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle.
On successful completion, tolower() and tolower_l() return the lower-case letter corresponding to the argument passed. Otherwise, it returns the argument unchanged.
No errors are defined.
See attributes(7) for descriptions of the following attributes: