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std::ctype::tolower,std::ctype::do_tolower(3) | C++ Standard Libary | std::ctype::tolower,std::ctype::do_tolower(3) |
NAME¶
std::ctype::tolower,std::ctype::do_tolower - std::ctype::tolower,std::ctype::do_tolower
Synopsis¶
Defined in header <locale>
public: (1)
CharT tolower( CharT c ) const;
public: (2)
const CharT* tolower( CharT* beg, const CharT* end ) const;
protected: (3)
virtual CharT do_tolower( CharT c ) const;
protected: (4)
virtual const CharT* do_tolower( CharT* beg, const CharT* end ) const;
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¶
toupper invokes do_toupper
(public member function)
tolower converts a character to lowercase
(function)
towlower converts a wide character to lowercase
(function)
2022.07.31 | http://cppreference.com |