识别UTF8无BOM

bool IsTextUtf8(char* lpText,int iLen)
{
	int cOctets;
	unsigned char chr;
	bool bAllAscii = true;
	
	cOctets = 0;
	
	for(int i = 0; i < iLen; ++i)
	{
		chr = *(lpText + i);
		if((chr & 0x80) != 0)
			bAllAscii = false;
		if(cOctets == 0)
		{
			if(chr >= 0x80)
			{
				do{
					chr <<= 1;
					cOctets++;
				}
				while((chr & 0x80) != 0);
				
				cOctets--;
				if(cOctets == 0)
					return false;
			}
		}
		else
		{
			if((chr & 0xc0) != 0x80)
				return false;
			cOctets--;
		}
	}

	if(cOctets > 0)
		return false;
	if(bAllAscii)
		return false;
	return true;
}