| Defined in header <locale> | ||
|---|---|---|
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
#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) |
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