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

See also

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