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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 a hexadecimal numeric character, zero otherwise. Notes std::isdigit and std::isxdigit are the only standard narrow charac- ter classification functions that are not affected by the currently installed C locale. although some implementations (e.g. Microsoft in 1252 codepage) may classify addi- tional 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 ); } Example // Run this code #include <cctype> #include <climits> #include <iostream> int main() { for (int c = 0; UCHAR_MAX >= c; ++c) if (isxdigit(c)) std::cout << static_cast<char>(c); std::cout << '\n'; } Output: 0123456789ABCDEFabcdef See also checks if a character is classified as a hexa- decimal digit by isxdigit(std::locale) a locale (function template) iswxdigit checks if a wide character is a hexadecimal character (function) C documentation for isxdigit ASCII values characters iscntrl isprint isspace isblank isgraph ispunct isalnum isalpha isupper islower isdigit isxdigit decimal hexadecimal octal iswcntrl isw- print iswspace iswblank iswgraph iswpunct iswalnum iswalpha iswupper iswlower iswdigit iswxdigit 08 \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 1013 \xA\xD \12\15 (\n, \v, \f, 0 0 0 0 0 0 0 0 0 0 0 0 \r) 1431 \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 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 GHIJKLMNOP 0 0 0 0 0 0 0 0 0 0 0 0 QRSTUVWXYZ 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 ghijklmnop 0 0 0 0 0 0 0 0 0 0 0 0 qrstuvwxyz 123126 \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) http://cppreference.com 2024.06.10 std::isxdigit(3)
NAME | Synopsis | Parameters | Return value | Notes | Example | Output: | See also
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