std::string 형변환 정리.

 
std::string to_str(int t) {
	 std::stringstream ss;
	 ss << t;
	 std::string str = ss.str();
	 return str;
 }
 std::string to_str(float t) {
	 std::stringstream ss;
	 ss << t;
	 std::string str = ss.str();
	 return str;
 }
 std::string to_str(long t) {
	 std::stringstream ss;
	 ss << t;
	 std::string str = ss.str();
	 return str;
 }
 std::string to_str(double t) {
	 std::stringstream ss;
	 ss << t;
	 std::string str = ss.str();
	 return str;
 }
 int from_str_to_int(std::string t) {
	 const char* buffer = t.c_str();
	 int i = atoi(buffer);
	 return i;
 }
 long from_str_to_long(std::string t) {
	 const char* buffer = t.c_str();
	 long i = atol(buffer);
	 return i;
 }
 double from_str_to_double(std::string t) {
	 const char* buffer = t.c_str();
	 double i = atof(buffer);
	 return i;
 }
 float from_str_to_float(std::string t) {
	 const char* buffer = t.c_str();
	 float i = atof(buffer);
	 return i;
 }