CTYPE(S) XENIX System V CTYPE(S)
Name
ctype, isalpha, isupper, islower, isdigit, isxdigit,
isalnum, isspace, ispunct, isprint, isgraph, iscntrl,
isascii, tolower, toupper, toascii - Classifies or converts
characters.
Syntax
#include <ctype.h>
int isalpha (c)
int c;
. . .
Description
These macros classify ASCII-coded integer values by table
lookup. Each returns nonzero for true, zero for false.
isascii is defined on all integer values; the rest are
defined only where isascii is true and on the single non-
ASCII value EOF (see stdio(S)).
isalpha c is a letter
isupper c is an uppercase letter
islower c is a lowercase letter
isdigit c is a digit [0-9]
isxdigit c is a hexidecimal digit [0-9], [A-F] or [a-
f]
isalnum c is an alphanumeric
isspace c is a space, tab, carriage return, newline,
vertical tab, or form feed
ispunct c is a punctuation character (neither control
nor alphanumeric)
isprint c is a printing character, octal 40 (space)
through octal 176 (tilde)
isgraph c is a printing character, like isprint
except false for space
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CTYPE(S) XENIX System V CTYPE(S)
iscntrl c is a delete character (octal 177) or
ordinary control character (less than octal
40).
isascii c is an ASCII character, code less than 0200
If the argument to any of these macros is not in the domain
of the function, the result is undefined.
The following macros convert to ASCII-coded integer values.
tolower and toupper are implemented as macros, but can be
undefined to get non-macro versions from libc. Non-
alphabetic values passed to toupper and tolower will be
returned unchanged.
tolower
If c is an uppercase letter, it is returned as a
lowercase letter
toupper
If c is a lowercase letter, it is returned as an
uppercase letter
toascii
c is truncated to the lowest 7 bits
See Also
ascii(M)
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