table of contents
std::isxdigit(3) | C++ Standard Libary | std::isxdigit(3) |
NAME¶
std::isxdigit - std::isxdigit
Synopsis¶
Defined in header <cctype>
int isxdigit( int ch );
Checks if the given character is a hexadecimal numeric character
(0123456789abcdefABCDEF).
The behavior is undefined if the value of ch is not representable as unsigned
char
and is not equal to EOF.
Parameters¶
ch - character to classify
Return value¶
Non-zero value if the character is an hexadecimal numeric character, zero otherwise.
Notes¶
isdigit and isxdigit are the only standard narrow character
classification functions
that are not affected by the currently installed C locale. although some
implementations (e.g. Microsoft in 1252 codepage) may classify additional
single-byte characters as digits.
Like all other functions from <cctype>, the behavior of std::isxdigit
is undefined
if the argument's value is neither representable as unsigned char nor equal
to EOF.
To use these functions safely with plain chars (or signed chars), the
argument
should first be converted to unsigned char:
bool my_isxdigit(char ch)
{
return std::isxdigit(static_cast<unsigned char>(ch));
}
Similarly, they should not be directly used with standard algorithms when the
iterator's value type is char or signed char. Instead, convert the value to
unsigned
char first:
int count_xdigits(const std::string& s)
{
return std::count_if(s.begin(), s.end(),
// static_cast<int(*)(int)>(std::isxdigit) // wrong
// [](int c){ return std::isxdigit(c); } // wrong
// [](char c){ return std::isxdigit(c); } // wrong
[](unsigned char c){ return std::isxdigit(c); } // correct
);
}
See also¶
checks if a character is classified as a hexadecimal digit by
isxdigit(std::locale) a locale
(function template)
iswxdigit checks if a character is a hexadecimal character
(function)
ASCII values characters iscntrl isprint isspace isblank isgraph ispunct
isalnum isalpha isupper islower isdigit isxdigit
decimal hexadecimal octal iswcntrl iswprint iswspace iswblank iswgraph
iswpunct iswalnum iswalpha iswupper iswlower iswdigit iswxdigit 0–8
\x0–\x8 \0–\10 control codes ?? 0 0 0 0 0 0 0 0 0 0 0 0
(NUL, etc.) 9 \x9 \11 tab (\t) ?? 0 0 ?? 0 ?? 0 0 0 0 0 0 0 0 0
whitespaces 10–13 \xA–\xD \12–\15 (\n, \v, \f, ?? 0 0 ??
0 0 0 0 0 0 0 0 0 0
\r) 14–31 \xE–\x1F \16–\37 control codes ?? 0 0 0 0 0 0
0 0 0 0 0 0 32 \x20 \40 space 0 ?? 0 ?? 0 ?? 0 0 0 0 0 0 0 0 0 33–47
\x21–\x2F \41–\57 !"#$%&'()*+,-./ 0 ?? 0 0 0 ?? 0 ??
0 0 0 0 0 0 0 48–57 \x30–\x39 \60–\71 0123456789 0 ?? 0
0 0 ?? 0 0 ?? 0 0 0 0 ?? 0 ?? 0 58–64 \x3A–\x40
\72–\100 :;<=>?@ 0 ?? 0 0 0 ?? 0 ?? 0 0 0 0 0 0 0 65–70
\x41–\x46 \101–\106 ABCDEF 0 ?? 0 0 0 ?? 0 0 ?? 0 ?? 0 ?? 0 0
0 ?? 0 71–90 \x47–\x5A \107–\132 GHIJKLMNOP 0 ?? 0 0 0
?? 0 0 ?? 0 ?? 0 ?? 0 0 0 0
QRSTUVWXYZ 91–96 \x5B–\x60 \133–\140 [\]^_` 0 ?? 0 0 0
?? 0 ?? 0 0 0 0 0 0 0 97–102 \x61–\x66 \141–\146 abcdef
0 ?? 0 0 0 ?? 0 0 ?? 0 ?? 0 0 ?? 0 0 ?? 0 103–122 \x67–\x7A
\147–\172 ghijklmnop 0 ?? 0 0 0 ?? 0 0 ?? 0 ?? 0 0 ?? 0 0 0
qrstuvwxyz 123–126 \x7B–\x7E \172–\176 {|}~ 0 ?? 0 0 0
?? 0 ?? 0 0 0 0 0 0 0 127 \x7F \177 backspace ?? 0 0 0 0 0 0 0 0 0 0 0 0
character (DEL)
2022.07.31 | http://cppreference.com |