conv(3)
NAME
toupper, tolower, _toupper, _tolower, toascii − translate characters
SYNTAX
#include <ctype.h>
int toupper (c)
int c;
int tolower (c)
int c;
int _toupper (c)
int c;
int _tolower (c)
int c;
int toascii (c)
int c;
DESCRIPTION
The toupper and tolower subroutines have as domain the range of getc(:): the integers from −1 through 255. If the argument of toupper represents a lowercase letter, the result is the corresponding uppercase letter. If the argument of tolower represents an uppercase letter, the result is the corresponding lowercase letter. All other arguments in the domain are returned unchanged.
The macros _toupper and _tolower, are macros that accomplish the same thing as toupper and tolower but have restricted domains and are faster. The macro _toupper requires a lowercase letter as its argument; its result is the corresponding uppercase letter. The macro _tolower requires an uppercase letter as its argument; its result is the corresponding lowercase letter. Arguments outside the domain cause undefined results.
The toascii yields its argument with all bits turned off that are not part of a standard ASCII character. It is intended for compatibility with other systems.