std::ctype<CharT>::tolower, std::ctype<CharT>::do_tolower
From cppreference.com
| Defined in header <locale>
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| public: CharT tolower( CharT c ) const; |
(1) | |
| public: const CharT* tolower( CharT* beg, const CharT* end ) const; |
(2) | |
| protected: virtual CharT do_tolower( CharT c ) const; |
(3) | |
| protected: virtual const CharT* do_tolower( CharT* beg, const CharT* end ) const; |
(4) | |
1,2) Public member function, calls the protected virtual member function
do_tolower of the most derived class.3) Converts the character c to lower case if a lower case form is defined by this locale.
4) For every character in the character array
[beg, end), for which a lower case form exists, replaces the character with that lower case form.Parameters
| c | - | character to convert |
| beg | - | pointer to the first character in an array of characters to convert |
| end | - | one past the end pointer for the array of characters to convert |
Return value
1,3) Lower case character or c if no lower case form is listed by this locale.
2,4) end
Notes
Only 1:1 character mapping can be performed by this function, e.g. the Greek uppercase letter 'Σ' has two lowercase forms, depending on the position in a word: 'σ' and 'ς'. A call to do_tolower cannot be used to obtain the correct lowercase form in this case.
Example
Run this code
#include <iostream> #include <locale> void try_lower(const std::ctype<wchar_t>& f, wchar_t c) { wchar_t up = f.tolower(c); if (up != c) std::wcout << "Lower case form of \'" << c << "' is " << up << '\n'; else std::wcout << '\'' << c << "' has no lower case form\n"; } int main() { std::locale::global(std::locale("en_US.utf8")); std::wcout.imbue(std::locale()); std::wcout << "In US English UTF-8 locale:\n"; auto& f = std::use_facet<std::ctype<wchar_t>>(std::locale()); try_lower(f, L'Σ'); try_lower(f, L'Ɛ'); try_lower(f, L'Ａ'); std::wstring str = L"HELLo, wORLD!"; std::wcout << "Lowercase form of the string '" << str << "' is "; f.tolower(&str[0], &str[0] + str.size()); std::wcout << '\'' << str << "'\n"; }
Output:
In US English UTF-8 locale: Lower case form of 'Σ' is σ Lower case form of 'Ɛ' is ɛ Lower case form of 'Ａ' is ａ Lowercase form of the string 'HELLo, wORLD!' is 'hello, world!'
See also
invokes do_toupper (public member function) | |
| converts a character to lowercase (function) | |
| converts a wide character to lowercase (function) |