유니코드 UTF-8 UTF-32LE 간 변환

std::string unicode2utf8(WCHAR* str)  
{  
    unsigned char u1, u2, u3, u4;
 
    std::string ret;  
    WCHAR uc;
 
	while(*str)
	{
		uc = *str;
		if (uc < 0x80) 
		{  
			ret += (char)*str;
		} 
		else if (uc < 0x800) 
		{  
			u2 = 0xC0 | uc >> 6;  
			u1 = 0x80 | uc & 0x3F;  
			ret+=u2;  
			ret+=u1;  
		} 
		else if (uc < 0x10000) 
		{  
			u3 = 0xE0 | uc >> 12;  
			u2 = 0x80 | uc >> 6 & 0x3F;  
			u1 = 0x80 | uc & 0x3F;  
			ret+=u3;  
			ret+=u2;  
			ret+=u1;  
		} 
		else if (uc < 0x200000) 
		{  
			u4 = 0xF0 | uc >> 18;  
			u3 = 0x80 | uc >> 12 & 0x3F;  
			u2 = 0x80 | uc >> 6 & 0x3F;  
			u1 = 0x80 | uc & 0x3F;  
			ret+=u4;  
			ret+=u3;  
			ret+=u2;  
			ret+=u1;  
		}  
		str++;
	}
 
    return ret;  
}