Passing template class as parameter

问题:

How do I pass a templated class to the constructor of another class? I am trying to pass a templated hash table class to a menu class which will allow me to then allow the user to decide the type of the hash table.

template <class T>
class OpenHash 
{
private: 
    vector <T> hashTab;
    vector <int> emptyCheck;
    int hashF(string);
    int hashF(int);
    int hashF(double);
    int hashF(float);
    int hashF(char); 

public:
    OpenHash(int);
    int getVectorCap();
    int addRecord (T);
    int sizeHash();
    int find(T);
    int printHash();
    int deleteEntry(T);
};

template <class T>
OpenHash<T>::OpenHash(int vecSize)
{
    hashTab.clear();
    hashTab.resize(vecSize);
    emptyCheck.resize(vecSize);
    for (int i=0; i < emptyCheck.capacity(); i++)   
    {
        emptyCheck.at(i) = 0;
    }
}

So I have this class Open hash that is templated, because it supposed to allow for any type to be added, I have this working if initiate a object of it in my main and change input types etc.

int main () 
{
   cout << "Please input the size of your HashTable" << endl;
   int vecSize = 0;
   cin >> vecSize;
   cout << "Please select the type of you hash table integer, string, float, "
           "double or char." << endl;
   bool typeChosen = false; 
   string typeChoice; 
   cin >> typeChoice;
while (typeChosen == false)
{
    if (typeChoice == "int" || "integer" || "i")
    {
        OpenHash<int> newTable(vecSize);
        typeChosen = true;
    }
    else if (typeChoice == "string" || "s")
    {
        OpenHash<string> newTable(vecSize);
       hashMenu<OpenHash> menu(newTable);
        typeChosen = true;

    }
    else if (typeChoice == "float" || "f")
    {
        OpenHash<float> newTable(vecSize);
        typeChosen = true; 
    }
    else if (typeChoice == "double" || "d")
    {
        OpenHash<double> newTable(vecSize);
        typeChosen = true;
    }
    else if (typeChoice == "char" || "c" || "character")
    {
        OpenHash<char> newTable(vecSize);
        typeChosen = true; 
    }
    else 
    {
        cout << "Incorrect type";
    }
}
return 0;
}

In my main I want to ask the user what type they which to make the hash table. depending what they enter it should create a instance of this class with the type they want and then pass this to another class called menu which should allow them to call functions from the hash class.

回答1:

You can use:

class Ctor {
public:
    Ctor(const Other<int>&);    // if you know the specific type
};

or:

class Ctor {
public:
    template<class T> 
    Ctor(const Other<T>&);      // if you don't know the specific type
};

Live demo