NAME | SYNOPSIS | DESCRIPTION | DIAGNOSTICS | ATTRIBUTES
All functions described in this page have the same syntax.
#include <ctype.h>int isalpha(int c);
These macros classify character-coded integer values by looking them up in a table. Each is a predicate returning nonzero for true, or zero for false.
c is a letter.
c is an upper-case letter.
c is a lower-case letter.
c is a digit [0-9].
c is a hexadecimal digit [0-9], [A-F] or [a-f].
c is an alphanumeric (letter or digit).
c is a space, tab, carriage return, new-line, vertical tab, or form-feed.
c is a punctuation character (neither control nor alphanumeric).
c is a printing character, code 040 (space) to 0176 (tilde).
c is a printing character, like isprint except for space.
c is a delete character (0177) or an ordinary control character (less than 040).
The conversion functions and macros translate a character from lowercase (uppercase) to uppercase (lowercase).
If c is a character for which isupper is true and there is a corresponding lowercase character, tolower returns the corresponding lowercase character. Otherwise, the character is returned unchanged.
If c is a character for which islower is true and there is a corresponding uppercase character, toupper returns the corresponding uppercase character. Otherwise, the character is returned unchanged.
If the argument to any of these macros is not in the domain of the function, the result is undefined.
See attributes(5) for descriptions of the following attributes:
ATTRIBUTE TYPE | ATTRIBUTE VALUE |
---|---|
Interface Stability | Evolving |
NAME | SYNOPSIS | DESCRIPTION | DIAGNOSTICS | ATTRIBUTES