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std::isupper(3) C++ Standard Libary std::isupper(3) NAME std::isupper - std::isupper Synopsis Defined in header <cctype> int isupper( int ch ); Checks if the given character is an uppercase character as classi- fied by the currently installed C locale. In the default "C" locale, isupper re- turns a nonzero value only for the uppercase letters (ABCDEFGHIJKLMNOPQRSTUVWXYZ). If isupper returns a nonzero value, it is guaranteed that iscntrl, isdigit, ispunct, and isspace return zero for the same character in the same C locale. 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 uppercase letter, zero other- wise. Notes Like all other functions from <cctype>, the behavior of std::isupper 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_isupper(char ch) { return std::isupper(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_uppers(const std::string& s) { return std::count_if(s.begin(), s.end(), // static_cast<int(*)(int)>(std::isupper) // wrong // [](int c){ return std::isupper(c); } // wrong // [](char c){ return std::isupper(c); } // wrong [](unsigned char c){ return std::isupper(c); } // correct ); } Example // Run this code #include <iostream> #include <cctype> #include <clocale> int main() { unsigned char c = '\xc6'; // letter in ISO-8859-1 std::cout << "isupper(\'\\xc6\', default C locale) returned " << std::boolalpha << (bool)std::isupper(c) << '\n'; std::setlocale(LC_ALL, "en_GB.iso88591"); std::cout << "isupper(\'\\xc6\', ISO-8859-1 locale) returned " << std::boolalpha << (bool)std::isupper(c) << '\n'; } Output: isupper('\xc6', default C locale) returned false isupper('\xc6', ISO-8859-1 locale) returned true See also isupper(std::locale) checks if a character is classified as upper- case by a locale (function template) iswupper checks if a wide character is an uppercase character (function) ASCII values characters iscntrl isprint is- space isblank isgraph ispunct isalnum isalpha isupper islower isdigit isxdigit decimal hexadecimal octal iswcntrl iswprint 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 2022.07.31 std::isupper(3)
NAME | Synopsis | Parameters | Return value | Notes | Example | Output: | See also
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