CODEWITHSUNDEEP
c++vector
A73rnA
A73rnA

Reputation: 151

dynamically allocating a vector

is it possible to dynamically allocate a vector without specifying its Type ?

im creating a container class which should support all the numeric types it must creat a container vector which type will be specified later when the first number is pushed into it .

first of all is this code correct ? 

private :
        vector<int> stk ;

public :
    template <typename Typ> 
    void push (Typ input) 
    {
        vector<Typ> temp ;
                    stk = temp ;
    }

second : i somehow need to dynamically allocate the "stk" vector without specifying the type .

Upvotes: 2

Views: 207

Answers (3)

liuyu
liuyu

Reputation: 1404

If this is C++ code, then templates are specialized at compile time. You cannot delay the allocation of a vector -- or any other template class instance -- to runtime.

A workaround would be to customize your own numeric class hierarchy with base class, say CNumeric, and allocate a vector of CNumeric*. Then the vector can accommodate any numeric type in your own class hierarchy. But of course, this workaround can be very inefficient.

Upvotes: 2

Thomas
Thomas

Reputation: 2163

Usually you don't need to change the type of things at runtime (and you can't in C++). Typically you want to change the design of your program.

If you really want to do this, you could use a union type that can hold one of a different number of things like here:

union A {
  int i;
  float f;
  double d;
};

and then store a vector of A.

Upvotes: 0

user995502
user995502

Reputation:

You haven't explained the problem correctly or you haven't understood what you really need.

If I understand correctly this is what you are looking for. 

template<typename Typ>
class A {
private :
        vector<Typ> stk ;

public :

    void push (Typ input) 
    {

         stk.push_back(input) ;

    }
}

Upvotes: 1

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