Well the well known way to do that is using the stream operator :

 #include <sstream>

 stringstream s;
 int i;
 
 s << i;

 string converted(s.str());

Of course you can generalise it for any type using a template function ^^

 #include <sstream>

 template<typename T>
 std::string toString(const T& value)
 {
 std::ostringstream oss;
 oss << value;
 return oss.str();
 }