std::btowc (3) - Linux Manuals

std::btowc: std::btowc

NAME

std::btowc - std::btowc

Synopsis

Defined in header <cwchar>
std::wint_t btowc( int c );

Widens a single-byte character c to its wide character equivalent.
Most multibyte character encodings use single-byte codes to represent the characters from the ASCII character set. This function may be used to convert such characters to wchar_t.

Parameters

c - single-byte character to widen

Return value

WEOF if c is EOF.
Wide character representation of c if (unsigned char)c is a valid single-byte character in the initial shift state, WEOF otherwise.

Example

// Run this code

  #include <iostream>
  #include <cwchar>
  #include <clocale>

  void try_widen(char c)
  {
      std::wint_t w = std::btowc(c);
      if(w != WEOF)
          std::cout << "The single-byte character " << +(unsigned char)c
                    << " widens to " << +w << '\n';
      else
          std::cout << "The single-byte character " << +(unsigned char)c
                    << " failed to widen\n";
  }

  int main()
  {
      std::setlocale(LC_ALL, "lt_LT.iso88594");
      std::cout << std::hex << std::showbase << "In Lithuanian ISO-8859-4 locale:\n";
      try_widen('A');
      try_widen('\xdf'); // German letter ß (U+00df) in ISO-8859-4
      try_widen('\xf9'); // Lithuanian letter ų (U+0173) in ISO-8859-4

      std::setlocale(LC_ALL, "lt_LT.utf8");
      std::cout << "In Lithuanian UTF-8 locale:\n";
      try_widen('A');
      try_widen('\xdf');
      try_widen('\xf9');
  }

Output:

  In Lithuanian ISO-8859-4 locale:
  The single-byte character 0x41 widens to 0x41
  The single-byte character 0xdf widens to 0xdf
  The single-byte character 0xf9 widens to 0x173
  In Lithuanian UTF-8 locale:
  The single-byte character 0x41 widens to 0x41
  The single-byte character 0xdf failed to widen
  The single-byte character 0xf9 failed to widen