NAME
isalpha —
alphabetic character test
LIBRARY
library “libc”
SYNOPSIS
#include
<ctype.h>
int
isalpha(int
c);
int
isalpha_l(int
c, locale_t
loc);
DESCRIPTION
Theisalpha()
function tests for any character for which
isupper(3) or
islower(3) is true. The value of the argument must be representable as
an unsigned char or the value of
EOF.
In the ASCII character set, this includes the following characters (with their numeric values shown in octal):
| 101 ``A'' | 102 ``B'' | 103 ``C'' | 104 ``D'' | 105 ``E'' |
| 106 ``F'' | 107 ``G'' | 110 ``H'' | 111 ``I'' | 112 ``J'' |
| 113 ``K'' | 114 ``L'' | 115 ``M'' | 116 ``N'' | 117 ``O'' |
| 120 ``P'' | 121 ``Q'' | 122 ``R'' | 123 ``S'' | 124 ``T'' |
| 125 ``U'' | 126 ``V'' | 127 ``W'' | 130 ``X'' | 131 ``Y'' |
| 132 ``Z'' | 141 ``a'' | 142 ``b'' | 143 ``c'' | 144 ``d'' |
| 145 ``e'' | 146 ``f'' | 147 ``g'' | 150 ``h'' | 151 ``i'' |
| 152 ``j'' | 153 ``k'' | 154 ``l'' | 155 ``m'' | 156 ``n'' |
| 157 ``o'' | 160 ``p'' | 161 ``q'' | 162 ``r'' | 163 ``s'' |
| 164 ``t'' | 165 ``u'' | 166 ``v'' | 167 ``w'' | 170 ``x'' |
| 171 ``y'' | 172 ``z'' |
The
isalpha_l()
function takes an explicit locale argument, whereas the
isalpha() function uses the current global or
per-thread locale.
RETURN VALUES
The isalpha() function returns zero if the
character tests false and returns non-zero if the character tests true.
COMPATIBILITY
The 4.4BSD extension of accepting
arguments outside of the range of the unsigned char
type in locales with large character sets is considered obsolete and may not
be supported in future releases. The iswalpha()
function should be used instead.
SEE ALSO
ctype(3), islower(3), isupper(3), iswalpha(3), xlocale(3), ascii(7)
STANDARDS
The isalpha() function conforms to
ISO/IEC 9899:1990 (“ISO C90”).
The isalpha_l() function conforms to
IEEE Std 1003.1-2008 (“POSIX.1”).