Question

I wrote class with template. class has map as member and some getxxx() / setxxx() member functions.

template<typename T1,typename T2>
class C1{
    map<T1,T2> M;
public:
    map<T1,T2> getM();
    T2 getMvalue(T1 Key);
    void setM(T1 key,T2 Value);
};

here I want to implement getMvalue(), where it recieves key as argument and returns the corresponding “value” if “key” is available in mapM.

It look something like…

template<typename TKey,typename TValue>
T2 C1<T1,T2>::getMvalue(T1 Key){
    if(M.count(Key)>0)
        return M[Key];
    else
        return(???);
};

Here I need to use something in place of ???. keeping in mind that return type of function is T2, which can be anything depending on user decision.
How can i replace “???” and with what?

Answer 1

I would encourage you to use the TryGet pattern

template<typename TKey,typename TValue>
bool C1<T1,T2>::tryGetMvalue(T1 key, T2& value){
    if(M.count(key)>0) {
        value = objProperties[key];
        return true;
    }
    return false;
};