| Defined in header <locale> | ||
|---|---|---|
public: bool always_noconv() const; | (1) | |
protected: virtual bool do_always_noconv() const; | (2) |
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 to use bulk character copy instead of calling std::codecvt::in if it is known that the locale imbued in the std::basic_filebuf does not perform any conversions.
Exceptions
| (none) | (until C++11) |
noexcept specification: noexcept | (since C++11) |
Example
#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
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