std::btowc (3) Linux Manual Page

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

See also

          narrows a wide character to a single-byte narrow character, if possible
wctob (function)
do_widen converts a character or characters from char to charT
          (virtual protected member function of std::ctype<CharT>)
[virtual]