std::wstring_convert::converted(3)

NAME
std::wstring_convert::converted - std::wstring_convert::converted

Synopsis
   Defined in header <locale>
   std::size_t converted() const noexcept;
   Returns the number of source characters that were processed by the most recent
   from_bytes() or to_bytes().

Return value
   The number of characters consumed by the most recent conversion operation.

Example
// Run this code
 #include <codecvt>
 #include <iostream>
 #include <locale>
 #include <string>
 int main()
 {
     std::string utf8 = "z\u00df\u6c34\U0001d10b"; // or u8"zß水𝄋"
                    // or "\x7a\xc3\x9f\xe6\xb0\xb4\xf0\x9d\x84\x8b";
     std::cout << "original UTF-8 string size: " << utf8.size() << '\n';
     // the UTF-8 - UTF-32 standard conversion facet
     std::wstring_convert<std::codecvt_utf8<char32_t>, char32_t> cvt;
     // UTF-8 to UTF-32
     std::u32string utf32 = cvt.from_bytes(utf8);
     std::cout << "UTF-32 string size: " << utf32.size() << '\n';
     std::cout << "converted() == " << cvt.converted() << '\n';
     // UTF-32 to UTF-8
     utf8 = cvt.to_bytes(utf32);
     std::cout << "new UTF-8 string size: " << utf8.size() << '\n';
     std::cout << "converted() == " << cvt.converted() << '\n';
 }

Output:
 original UTF-8 string size: 10
 UTF-32 string size: 4
 converted() == 10
 new UTF-8 string size: 10
 converted() == 4
   Defect reports
   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.
      DR Applied to Behavior as published Correct behavior
   LWG 2174 C++11 wstring_convert::converted was not required to required
                       be noexcept

See also
   to_bytes converts a wide string into a byte string
              (public member function)
   from_bytes converts a byte string into a wide string
              (public member function)