# std::btowc

From cppreference.com
< cpp‎ | string‎ | multibyte

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 [virtual] | converts a character or characters from `char` to `charT` (virtual protected member function of `std::ctype<CharT>`)

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