Converts an uppercase character to lowercase.
#include <ctype.h> int _tolower (int character);
The _tolower macro is equivalent to the tolower function except that its argument must be an uppercase letter (not lowercase, not EOF).
The _tolower macro should not be used with arguments that contain side-effect operations. For instance, the following example will not return the expected result:
d = _tolower (c++);
| x | The lowercase letter corresponding to the argument. |