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(3s): the integers from −1 through 255. If the argument of toupper represents a lower-case letter, the result is the corresponding upper-case letter. If the argument of tolower represents an upper-case letter, the result is the corresponding lower-case letter. All other arguments in the domain are returned unchanged.
The _toupper and _tolower , macros are similar to toupper and tolower except they have restricted domains and are faster. _toupper requires a lower-case letter as its argument; its result is the corresponding upper-case letter. The _tolower macro requires an upper-case letter as its argument. Its result is the corresponding lower-case letter. Arguments outside the domain cause undefined results.
The toascii subroutine 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.