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c++templates
Mathew Kurian
Mathew Kurian

Reputation: 6039

Template in C++ with raw type

In Java, we can do something like this:

ArrayList arrayList = new ArrayList<String>(); 
// Notice that String is not mentioned in the first declaration of array

AS OPPOSED TO 

ArrayList<String> arrayList = new ArrayList<String>();

How can we something in similar in C++?

Upvotes: 0

Views: 1144

Answers (2)

Joe Z
Joe Z

Reputation: 17936

Not in exactly the way you've written.

What you can do is one of the following, depending on what you're actually trying to accomplish:

  • In C++11, you can use auto to automatically adapt to the type: auto = new ArrayList<String>();. This doesn't give you polymorphism, but it does save you typing the typename on the left hand side.
  • If you want polymorphism, you can add a level to your class hierarchy, and make the left-hand side point to a parent class.

Here's an example of the second approach:

class IArrayList   // define a pure virtual ArrayList interface
{
     // put your interface pure virtual method declarations here
};

template <typename T>
class ArrayList : public IArrayList
{
     // put your concrete implementation here
};

Then, you could say in your code:

IArrayList* arrayList1 = new ArrayList<string>();
IArrayList* arrayList2 = new ArrayList<double>();

...and so on.

Upvotes: 4

tenos
tenos

Reputation: 959

In c++， you can not use vector array = new vector<string>(), but in c++11, you can use auto keyword: auto p = new vector<string>(), it is the same as vector<string> *p = new vector<string>().Hope that my answer can help you.

Upvotes: 2

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