Difference between revisions of "cpp/locale/tolower"
From cppreference.com
m (Text replace - "{{cpp|" to "{{c|") |
Andreas Krug (Talk | contribs) m ({{c}}, fmt, headers sorted) |
||
| (7 intermediate revisions by 3 users not shown) | |||
| Line 1: | Line 1: | ||
| − | {{cpp/title | tolower{{small|(std::locale)}}}} | + | {{cpp/title|tolower{{small|(std::locale)}}}} |
| − | {{cpp/locale/ | + | {{cpp/locale/navbar}} |
| − | + | {{ddcl|header=locale| | |
| − | {{ddcl | header=locale | | + | template< class CharT > |
| − | template< class | + | CharT tolower( CharT ch, const locale& loc ); |
| − | + | ||
}} | }} | ||
| − | Converts the character {{ | + | Converts the character {{c|ch}} to lowercase if possible, using the conversion rules specified by the given locale's {{lc|std::ctype}} facet. |
===Parameters=== | ===Parameters=== | ||
| − | {{ | + | {{par begin}} |
| − | {{ | + | {{par|ch|character}} |
| − | {{ | + | {{par|loc|locale}} |
| − | {{ | + | {{par end}} |
===Return value=== | ===Return value=== | ||
| − | Returns the lowercase form of {{ | + | Returns the lowercase form of {{c|ch}} if one is listed in the locale, otherwise return {{c|ch}} unchanged. |
===Notes=== | ===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 {{ | + | 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 {{lc|std::tolower}} cannot be used to obtain the correct lowercase form in this case. |
===Possible implementation=== | ===Possible implementation=== | ||
| − | {{eq fun | + | {{eq fun |
| − | + | |1= | |
| − | template< class | + | template<class CharT> |
| − | + | CharT tolower(CharT ch, const std::locale& loc) | |
| − | return std::use_facet<std::ctype< | + | { |
| + | return std::use_facet<std::ctype<CharT>>(loc).tolower(ch); | ||
} | } | ||
}} | }} | ||
| Line 32: | Line 32: | ||
===Example=== | ===Example=== | ||
{{example | {{example | ||
| − | + | |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'; | ||
| + | } | ||
| + | |p=true | ||
| + | |output= | ||
| + | in the default locale, tolower(0x190) = 0x190 | ||
| + | in Unicode locale, tolower(0x190) = 0x25b | ||
}} | }} | ||
===See also=== | ===See also=== | ||
| − | {{ | + | {{dsc begin}} |
| − | {{ | + | {{dsc inc|cpp/locale/dsc toupper}} |
| − | {{ | + | {{dsc inc|cpp/string/byte/dsc tolower}} |
| − | {{ | + | {{dsc inc|cpp/string/wide/dsc towlower}} |
| − | {{ | + | {{dsc end}} |
| + | |||
| + | {{langlinks|de|es|fr|it|ja|pt|ru|zh}} | ||
Latest revision as of 10:33, 6 October 2023
| Defined in header <locale>
|
||
| template< class CharT > CharT tolower( CharT ch, const locale& loc ); |
||
Converts the character ch to lowercase if possible, using the conversion rules specified by the given locale's std::ctype facet.
Contents |
[edit] Parameters
| ch | - | character |
| loc | - | locale |
[edit] Return value
Returns the lowercase form of ch if one is listed in the locale, otherwise return ch unchanged.
[edit] 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.
[edit] Possible implementation
template<class CharT> CharT tolower(CharT ch, const std::locale& loc) { return std::use_facet<std::ctype<CharT>>(loc).tolower(ch); } |
[edit] 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
[edit] 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) |
