std::isalpha
| Defined in header <cctype>
|
||
| int isalpha( int ch ); |
||
Checks if the given character is an alphabetic character as classified by the currently installed C locale. In the default locale, the following characters are alphanumeric:
- uppercase letters
ABCDEFGHIJKLMNOPQRSTUVWXYZ - lowercase letters
abcdefghijklmnopqrstuvwxyz
In locales other than "C", an alphabetic character is a character for which std::isupper() or std::islower() returns true or any other character considered alphabetic by the locale. In any case, std::iscntrl(), std::isdigit(), std::ispunct() and std::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.
Contents |
[edit] Parameters
| ch | - | character to classify |
[edit] Return value
Non-zero value (true) if the character is an alphabetic character, 0 (false) otherwise.
[edit] Example
Demonstrates the use of isalpha() with different locales (OS-specific).
#include <iostream> #include <cctype> #include <clocale> int main() { unsigned char c = '\xdf'; // German letter ß in ISO-8859-1 std::cout << "isalpha(\'\\xdf\', default C locale) returned " << std::boolalpha << (bool)std::isalpha(c) << '\n'; std::setlocale(LC_ALL, "de_DE.iso88591"); std::cout << "isalpha(\'\\xdf\', ISO-8859-1 locale) returned " << std::boolalpha << (bool)std::isalpha(c) << '\n'; }
Output:
isalpha('\xdf', default C locale) returned false
isalpha('\xdf', ISO-8859-1 locale) returned true[edit] See also
| checks if a character is classified as alphabetic by a locale (function template) | |
| checks if a wide character is alphabetic (function) | |
| C documentation for isalpha
| |
| ASCII values (hex) |
characters |
isalpha |
||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 - 8 | 0x00-0x08
|
control codes (NUL, etc.)
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 9 | 0x09
|
tab (\t)
|
≠0
|
0
|
≠0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 10 - 13 | 0x0A-0x0D
|
whitespaces (\n,\v,\f,\r)
|
≠0
|
0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 14 - 31 | 0x0E-0x1F
|
control codes | ≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 32 | 0x20
|
space | 0
|
≠0
|
≠0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 33 - 47 | 0x21-0x2F
|
!"#$%&'()*+,-./
|
0
|
≠0
|
0
|
0
|
≠0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 48 - 57 | 0x30-0x39
|
0123456789
|
0
|
≠0
|
0
|
0
|
≠0
|
0
|
≠0
|
0
|
0
|
0
|
≠0
|
≠0
|
| 58 - 64 | 0x3a-0x40
|
:;<=>?@
|
0
|
≠0
|
0
|
0
|
≠0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 65 - 70 | 0x41-0x46
|
ABCDEF
|
0
|
≠0
|
0
|
0
|
≠0
|
0
|
≠0
|
≠0
|
≠0
|
0
|
0
|
≠0
|
| 71 - 90 | 0x47-0x5A
|
GHIJKLMNOPQRSTUVWXYZ
|
0
|
≠0
|
0
|
0
|
≠0
|
0
|
≠0
|
≠0
|
≠0
|
0
|
0
|
0
|
| 91 - 96 | 0x5B-0x60
|
[\]^_`
|
0
|
≠0
|
0
|
0
|
≠0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 97 -102 | 0x61-0x66
|
abcdef
|
0
|
≠0
|
0
|
0
|
≠0
|
0
|
≠0
|
≠0
|
0
|
≠0
|
0
|
≠0
|
| 103-122 | 0x67-0x7A
|
ghijklmnopqrstuvwxyz
|
0
|
≠0
|
0
|
0
|
≠0
|
0
|
≠0
|
≠0
|
0
|
≠0
|
0
|
0
|
| 123-126 | 0x7B-0x7E
|
{|}~
|
0
|
≠0
|
0
|
0
|
≠0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 127 | 0x7F
|
backspace character (DEL)
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|