cpp/locale/ctype/tolower

@1,2@ public member function, calls the protected virtual member function of the most derived class. @3@ Converts the character to lower case if a lower case form is defined by this locale. @4@ For every character in the character array, for which a lower case form exists, replaces the character with that lower case form.

Return value
@1,3@ lower case character or if no lower case form is listed by this locale. @2,4@.