Checks if the given character is an alphabetic character, i.e. either an uppercase letter (ABCDEFGHIJKLMNOPQRSTUVWXYZ
), or a lowercase letter (abcdefghijklmnopqrstuvwxyz
).
In locales other than "C", an alphabetic character is a character for which isupper() or islower() returns true or any other character considered alphabetic by the locale. In any case, iscntrl(), isdigit(), ispunct() and isspace() will return false for this character.
The behavior is undefined if the value of ch is not representable as unsigned char and is not equal to EOF.
[edit] Parameters ch - character to classify [edit] Return valueNon-zero value if the character is an alphabetic character, zero otherwise.
[edit] ExampleDemonstrates the use of isalpha
with different locales (OS-specific).
#include <ctype.h> #include <locale.h> #include <stdio.h> int main(void) { unsigned char c = '\xdf'; // German letter à in ISO-8859-1 printf("isalpha('\\xdf') in default C locale returned %d\n", !!isalpha(c)); setlocale(LC_CTYPE, "de_DE.iso88591"); printf("isalpha('\\xdf') in ISO-8859-1 locale returned %d\n", !!isalpha(c)); }
Possible output:
isalpha('\xdf') in default C locale returned 0 isalpha('\xdf') in ISO-8859-1 locale returned 1[edit] References
isalpha
iswalpha
\x0
â\x8
\0
â\10
control codes (NUL
, etc.) â 0
0
0
0
0
0
0
0
0
0
0
0
9 \x9
\11
tab (\t
) â 0
0
â 0
â 0
0
0
0
0
0
0
0
0
10â13 \xA
â\xD
\12
â\15
whitespaces (\n
, \v
, \f
, \r
) â 0
0
â 0
0
0
0
0
0
0
0
0
0
14â31 \xE
â\x1F
\16
â\37
control codes â 0
0
0
0
0
0
0
0
0
0
0
0
32 \x20
\40
space 0
â 0
â 0
â 0
0
0
0
0
0
0
0
0
33â47 \x21
â\x2F
\41
â\57
!"#$%&'()*+,-./
0
â 0
0
0
â 0
â 0
0
0
0
0
0
0
48â57 \x30
â\x39
\60
â\71
0123456789
0
â 0
0
0
â 0
0
â 0
0
0
0
â 0
â 0
58â64 \x3A
â\x40
\72
â\100
:;<=>?@
0
â 0
0
0
â 0
â 0
0
0
0
0
0
0
65â70 \x41
â\x46
\101
â\106
ABCDEF
0
â 0
0
0
â 0
0
â 0
â 0
â 0
0
0
â 0
71â90 \x47
â\x5A
\107
â\132
GHIJKLMNOP
QRSTUVWXYZ
0
â 0
0
0
â 0
0
â 0
â 0
â 0
0
0
0
91â96 \x5B
â\x60
\133
â\140
[\]^_`
0
â 0
0
0
â 0
â 0
0
0
0
0
0
0
97â102 \x61
â\x66
\141
â\146
abcdef
0
â 0
0
0
â 0
0
â 0
â 0
0
â 0
0
â 0
103â122 \x67
â\x7A
\147
â\172
ghijklmnop
qrstuvwxyz
0
â 0
0
0
â 0
0
â 0
â 0
0
â 0
0
0
123â126 \x7B
â\x7E
\173
â\176
{|}~
0
â 0
0
0
â 0
â 0
0
0
0
0
0
0
127 \x7F
\177
backspace character (DEL
) â 0
0
0
0
0
0
0
0
0
0
0
0
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