| _toupper | Function (Macro)

ctype.h

short _toupper (short c);

Translates uppercase characters to lowercase.

_toupper does the same conversion as toupper or toextupper, except that it should be used only when c is known to be lowercase (either ordinary or foreign). It is faster, and generates much shorter code than toupper. _toupper returns the converted value of c if it is lowercase; otherwise, the result is undefined. _toupper is a simple macro.