std::tolower(std::locale)
From cppreference.com
| Defined in header <locale>
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template< class CharT >
CharT tolower( CharT ch, const locale& loc );
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Converts the character ch to lowercase if possible, using the conversion rules specified by the given locale's std::ctype facet.
Parameters
| ch | - | character |
| loc | - | locale |
Return value
Returns the lowercase form of ch if one is listed in the locale, otherwise return ch unchanged.
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 std::tolower cannot be used to obtain the correct lowercase form in this case.
Possible implementation
template<class CharT>
CharT tolower(CharT ch, const std::locale& loc)
{
return std::use_facet<std::ctype<CharT>>(loc).tolower(ch);
}
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Example
Run this code
#include <cwctype>
#include <iostream>
#include <locale>
int main()
{
wchar_t c = L'\u0190'; // Latin capital open E ('Ɛ')
std::cout << std::hex << std::showbase;
std::cout << "in the default locale, tolower(" << (std::wint_t)c << ") = "
<< (std::wint_t)std::tolower(c, std::locale()) << '\n';
std::cout << "in Unicode locale, tolower(" << (std::wint_t)c << ") = "
<< (std::wint_t)std::tolower(c, std::locale("en_US.utf8")) << '\n';
}
Possible output:
in the default locale, tolower(0x190) = 0x190
in Unicode locale, tolower(0x190) = 0x25b
See also
| converts a character to uppercase using the ctype facet of a locale (function template) | |
| converts a character to lowercase (function) | |
| converts a wide character to lowercase (function) |
