抽象函数和变量参数列表 [英] Abstract functions and variable arguments list

问题描述

我有一个抽象类，我想知道是否可以定义一个带有可变参数列表的抽象函数?

I have an abstract class an I like to know if it's possible to define an abstract function with variable arguments list?

如果可能，请举个例子.

Give me an example if it's possible.

推荐答案

是的，原则上是可以的.下面是一个例子.您可以在此处看到输出.

Yes, it is possible in principle. An example follows below. You can see the output here.

另请阅读此处和此处

#include <iostream>
#include <cstdarg>

using namespace std;


class AbstractClass{

public:

  virtual double average(int num, ... ) = 0;


};


class ConcreteClass : public AbstractClass{
public:

   virtual double average(int num, ... ) 
   {
      va_list arguments;                     // A place to store the list of arguments
      double sum = 0;

      va_start ( arguments, num );           // Initializing arguments to store all values after num
      for ( int x = 0; x < num; x++ )        // Loop until all numbers are added
        sum += va_arg ( arguments, double ); // Adds the next value in argument list to sum.
      va_end ( arguments );                  // Cleans up the list

      return sum / num;                      // Returns the average
  }



};



int main()
{
    AbstractClass* interface = new ConcreteClass();
    cout << interface->average( 3 , 20 ,30 , 40 );

    return 0;
}

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