Reading characters from UTF-8 Encoded File

Due to the fact that UTF-8 encoded characters have a variable length, you have to check each byte read. A possible solution (using file a file handle opened in binary mode) would be:
 

typedef struct {
    int nLen;
    unsigned char cByte[6];
} utf8char_t;
 
// Read UTF-8 char into struct
// Return number of UTF-8 bytes read (0 upon EOF, -1 upon invalid codes)
int read_utf8_char(FILE *f, utf8char_t& tChar)
{
    tChar.nLen = 0;
    if (feof(f))
        return 0;
    unsigned char c = tChar.cByte[0] = 
        static_cast<unsigned char>(fgetc(f));
    if (c & 0x80)
    {
        while (c & 0x80)
        {
            ++tChar.nLen;
            c <<= 1;
        }
        for (int i = 1; i < tChar.nLen && i < 6)
        {
            if (feof(f))
                return 0;
            tChar.cByte[i] = static_cast<unsigned char>(fgetc(f));
            if ((tChar.cByte[i] & 0xC0) != 0x80)
                return -1;
        }
        if (tChar.nLen >= 6)
            return -1;
    }
    else
        tChar.nLen = 1;
    return tChar.nLen;
}

 
Please nothe that this example does not check for all possible wrong UTF-8 codes.