# btowc

From cppreference.com
< c‎ | string‎ | multibyte

Defined in header `<wchar.h>` |  |
wint_t btowc( int c ); |  | (since C95)

Widens a single-byte character `c` (reinterpreted as unsigned char) 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 <stdio.h>
    #include <wchar.h>
    #include <locale.h>
    #include <assert.h>

    void try_widen(unsigned char c)
    {
        wint_t w = btowc(c);
        if(w != WEOF)
            printf("The single-byte character %#x widens to %#x\n", c, w);
        else
            printf("The single-byte character %#x failed to widen\n", c);
    }

    int main(void)
    {
        char *loc = setlocale(LC_ALL, "lt_LT.iso88594");
        assert(loc);
        printf("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

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

Possible 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

### References

- C11 standard (ISO/IEC 9899:2011):

  - 7.29.6.1.1 The btowc function (p: 441)

- C99 standard (ISO/IEC 9899:1999):

  - 7.24.6.1.1 The btowc function (p: 387)

### See also

wctob (C95) | narrows a wide character to a single-byte narrow character, if possible (function)
C++ documentation for btowc

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