std::isalnum
cppreference.com
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int isalnum( int ch ); |
||
, - , C. -:
- (
0123456789) - (
ABCDEFGHIJKLMNOPQRSTUVWXYZ) - (
abcdefghijklmnopqrstuvwxyz)
, ch unsigned char EOF.
| ch |
, -, 0.
<cctype>, std::isalnum , unsigned char EOF. char ( signed char), unsigned char:
bool my_isalnum(char ch)
{
return std::isalnum(static_cast<unsigned char>(ch));
}
, , char signed char. unsigned char:
int count_alnums(const std::string& s)
{
return std::count_if(s.begin(), s.end(),
// static_cast<int(*)(int)>(std::isalnum) //
// [](int c){ return std::isalnum(c); } //
// [](char c){ return std::isalnum(c); } //
[](unsigned char c){ return std::isalnum(c); } //
);
}
std::isalnum ( ).
#include <cctype>
#include <clocale>
#include <iostream>
int main()
{
unsigned char c = '\xdf'; // ISO-8859-1
std::cout << "isalnum(\'\\xdf\', C ) "
<< std::boolalpha << static_cast<bool>(std::isalnum(c)) << '\n';
if (std::setlocale(LC_ALL, "de_DE.iso88591"))
std::cout << "isalnum(\'\\xdf\', ISO-8859-1) "
<< static_cast<bool>(std::isalnum(c)) << '\n';
}
:
isalnum('\xdf', C ) false
isalnum('\xdf', ISO-8859-1) true
| , - ( ) | |
| , - () | |
C isalnum
| |
| ASCII | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| - | -- | - | |||||||||||||
| 08 | \x0\x8
|
\0\10
|
(NUL, ..)
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 9 | \x9
|
\11
|
(\t)
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 1013 | \xA\xD
|
\12\15
|
(\n, \v, \f, \r)
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 1431 | \xE\x1F
|
\16\37
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
| |
| 32 | \x20
|
\40
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
| |
| 3347 | \x21\x2F
|
\41\57
|
!"#$%&'()*+,-./
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 4857 | \x30\x39
|
\60\71
|
0123456789
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 5864 | \x3A\x40
|
\72\100
|
:;<=>?@
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 6570 | \x41\x46
|
\101\106
|
ABCDEF
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 7190 | \x47\x5A
|
\107\132
|
GHIJKLMNOPQRSTUVWXYZ
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 9196 | \x5B\x60
|
\133\140
|
[\]^_`
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 97102 | \x61\x66
|
\141\146
|
abcdef
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 103122 | \x67\x7A
|
\147\172
|
ghijklmnopqrstuvwxyz
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 123126 | \x7B\x7E
|
\172\176
|
{|}~
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
| 127 | \x7F
|
\177
|
(DEL)
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|