C++ | cout, Print returned Object

I came to a Problem where i cant print a returned object via cout. I find it hard to describe so i wrote a very basic programm to show my problem. The compiler says Type mismatch in operator<<. The overloaded + Returns an Integer object, but why cant it be printed? "Test.cpp" ``` #include <iostream> #include "Integer.h" using namespace std; int main() { Integer int1(5); Integer int2(2); cout << (int1 + int2) << endl; // Here it fails cout << int2 << endl; // Works return 0; } ``` "Integer.cpp" ``` #include "Integer.h" Integer::Integer(int integer) { this->integer = integer; } int Integer::get_integer() return integer; } Integer Integer::operator +(Integer& integer) { return Integer(this->integer + integer.get_integer()); } ostream& operator<<(ostream& output, Integer& integer) { output << integer.get_integer(); return output; } ``` "Integer.h" ``` #include <iostream> using namespace std; class Integer { private: int integer; public: Integer(int integer); int get_integer(); Integer operator+(Integer& integer); }; ostream& operator<<(ostream& output, Integer& integer); ``` Thanks in advance