std::codecvt::always_noconv,do_always_noconv(3) | C++ Standard Libary | std::codecvt::always_noconv,do_always_noconv(3) |
NAME¶
std::codecvt::always_noconv,do_always_noconv - std::codecvt::always_noconv,do_always_noconv
Synopsis¶
Defined in header <locale>
public: (until C++11)
bool always_noconv() const throw();
public: (since C++11)
bool always_noconv() const noexcept; (1)
protected: (until C++11)
virtual bool do_always_noconv() const throw(); (2)
protected: (since C++11)
virtual bool do_always_noconv() const noexcept;
1) Public member function, calls the member function do_always_noconv of the
most
derived class.
2) Returns true if both do_in() and do_out() return std::codecvt_base::noconv
for
all valid inputs.
Return value¶
true if this conversion facet performs no conversions, false otherwise.
The non-converting specialization std::codecvt<char, char,
std::mbstate_t> returns
true
Notes¶
This function may be used e.g. in the implementation of
std::basic_filebuf::underflow and std::basic_filebuf::overflow to use bulk
character
copy instead of calling std::codecvt::in or std::codecvt::out if it is known
that
the locale imbued in the std::basic_filebuf does not perform any
conversions.
Example¶
// Run this code
#include <locale>
#include <iostream>
int main()
{
std::cout << "The non-converting char<->char
codecvt::always_noconv() returns "
<< std::boolalpha
<< std::use_facet<std::codecvt<char, char,
std::mbstate_t>>(
std::locale()
).always_noconv() << "\n"
<< "while wchar_t<->char codecvt::always_noconv() returns
"
<< std::use_facet<std::codecvt<wchar_t, char,
std::mbstate_t>>(
std::locale()
).always_noconv() << "\n";
}
Output:¶
The non-converting char<->char codecvt::always_noconv()
returns true
while wchar_t<->char codecvt::always_noconv() returns false
2022.07.31 | http://cppreference.com |