//try this one. it will yield more accurate result.
const bool BTStringMgr::isUtf8(const char *buf) {
int i, n;
register unsigned char c;
bool gotone = false;
#define F 0 /* character never appears in text */
#define T 1 /* character appears in plain ASCII text */
#define I 2 /* character appears in ISO-8859 text */
#define X 3 /* character appears in non-ISO extended ASCII (Mac, IBM PC) */
static const unsigned char text_chars[256] = {
/* BEL BS HT LF FF CR */
F, F, F, F, F, F, F, T, T, T, T, F, T, T, F, F, /* 0x0X */
/* ESC */
F, F, F, F, F, F, F, F, F, F, F, T, F, F, F, F, /* 0x1X */
T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x2X */
T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x3X */
T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x4X */
T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x5X */
T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x6X */
T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, F, /* 0x7X */
/* NEL */
X, X, X, X, X, T, X, X, X, X, X, X, X, X, X, X, /* 0x8X */
X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, /* 0x9X */
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xaX */
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xbX */
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xcX */
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xdX */
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xeX */
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I /* 0xfX */
};
/* *ulen = 0; */
for (i = 0; (c = buf[i ]); i++) {
if ((c & 0x80) == 0) { /* 0xxxxxxx is plain ASCII */
/*
* Even if the whole file is valid UTF-8 sequences,
* still reject it if it uses weird control characters.
*/
if (text_chars[c] != T)
return false;
} else if ((c & 0x40) == 0) { /* 10xxxxxx never 1st byte */
return false;
} else { /* 11xxxxxx begins UTF-8 */
int following;
if ((c & 0x20) == 0) { /* 110xxxxx */
following = 1;
} else if ((c & 0x10) == 0) { /* 1110xxxx */
following = 2;
} else if ((c & 0x08) == 0) { /* 11110xxx */
following = 3;
} else if ((c & 0x04) == 0) { /* 111110xx */
following = 4;
} else if ((c & 0x02) == 0) { /* 1111110x */
following = 5;
} else
return false;
for (n = 0; n < following; n++) {
i++;
if (!(c = buf[i ]))
goto done;
if ((c & 0x80) == 0 || (c & 0x40))
return false;
}
gotone = true;
}
}
done:
return gotone; /* don't claim it's UTF-8 if it's all 7-bit */
}
#undef F
#undef T
#undef I
#undef X
[ 此贴被XChinux在2005-09-19 16:50重新编辑 ]