Converts a character to lowercase.

    Format

      #include  <ctype.h>

      int tolower  (int character);

1 - Argument

 character

    An object of type int representable as an unsigned char or the
    value of EOF. For any other value, the behavior is undefined.

2 - Description

    If the argument represents an uppercase letter, and there is
    a corresponding lowercase letter, as defined by character
    type information in the program locale category LC_CTYPE, the
    corresponding lowercase letter is returned.

    If the argument is not an uppercase character, it is returned
    unchanged.

3 - Return Value

    x                  The lowercase letter corresponding to the
                       argument. Or, the unchanged argument, if it is
                       not an uppercase character.