isalpha3
Alphabetic character test
Usage
#include <ctype.h>
int
isalpha(int c);
Library
Standard C Library (libc, -lc)
Overview
The isalpha() 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 (preceded by their numeric values, 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'' |
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.
Releases
163 releases since Mac OS X 10.0; the text changed 5 times.