std::isalnum
From Cppreference
C++ Standard Library |
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Strings library |
Narrow null-terminated strings |
Defined in header <cctype>
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int isalnum( int ch );
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Checks if the given character is an alphanumeric character according to the current C locale, i.e. either a number (0123456789 in the default locale), an uppercase letter (ABCDEFGHIJKLMNOPQRSTUVWXYZ in the default locale), or a lowercase letter (abcdefghijklmnopqrstuvwxyz in the default locale).
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[edit] Parameters
ch | - | character |
[edit] Return value
non-zero value (true) if the character is an alphanumeric character, 0 (false) otherwise.
[edit] Example
Demonstrates the use of isalnum() with different locales (OS-specific).
#include <iostream> #include <cctype> #include <clocale> int main() { const char c = '\xdf'; // German letter ß in ISO-8859-1 std::cout << "isalnum(\'\\xdf\', default C locale) returned " << std::boolalpha << (bool)std::isalnum(c) << '\n'; std::setlocale(LC_ALL, "de_DE.iso88591"); std::cout << "isalnum(\'\\xdf\', ISO-8859-1 locale) returned " << std::boolalpha << (bool)std::isalnum(c) << '\n'; }
Output:
isalnum('\xdf', default C locale) returned false isalnum('\xdf', ISO-8859-1 locale) returned true
[edit] See also
ASCII values (hex) |
characters |
isalnum |
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0 - 8 | 0x00-0x08 | control codes (NUL, etc.) | ≠0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
9 | 0x09-0x0D | tab (\t) | ≠0 | 0 | ≠0 | ≠0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
10 - 13 | 0x09-0x0D | whitespace (\f,\v,\n,\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 | 01234567890 | 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 |
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checks if a character is classified as alphanumeric by a locale (function template) |
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checks if a wide character is alphanumeric (function) |