class SQLru {
int& rInt;
public:
    SQLru(int& Value) { 
        rInt = Value; 
    }
};


int main() {
    int Val = 100500;
    SQLru sql(Val);
    return 0;
}

main.cpp: In constructor ‘SQLru::SQLru(int&)’:
main.cpp:5:5: error: uninitialized reference member in ‘int&’ [-fpermissive]
     SQLru(int& Value) {
     ^~~~~
main.cpp:3:6: note: ‘int& SQLru::rInt’ should be initialized
 int& rInt;
      ^~~~

class SQLru {
const int& rInt;
public:
    SQLru(const int& Value) : rInt(Value) {}
};


int main() {
    const int Val = 100500;
    SQLru sql(Val);
    return 0;
}

...Program finished with exit code 0