std::ctype::tolower, std::ctype::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 <locale> #include <iostream> 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) |