在类中初始化向量

Question

I have the following problem. I have a class, say

class MyClass{
public:
  class MyNumber;
  MyClass(char const *filename);
  class MyNumber{
  public:
    MyNumber(int n) : n(n) {}
  private:
    int n;
  };

private:
  std::vector<MyNumber> mynumbers
};

Now I want to write a constructor for the class MyClass, which reads a file and depending on the content of the file initializes the vector mynumbers. What I did is the following

MyClass::Myclass (char const * filename){
  int num = 0;
  std::string line;
  std::getline(file, line);              
  std::stringstream ss(line);              
  ss >> num; 
  mynumbers(num,MyNumber(5));

}

But I get the error "type 'std::vector' does not provide a call operator". I also can't use a constructor initializer lists (at least I think so) since it depends on my input file how big my vector has to be. Can somebody tell me how this is done?

Answer 1

Just use the method assign

mynumbers.assign(num,MyNumber(5));

As for this statement

mynumbers(num,MyNumber(5));

then it corresponds to a call of a function operator. However the standard class std::vector does not has such an operator. The object mynumbers in the constructor was already created/ So you can only assign it with new values. You can not call its constructor a second time. On the other hand the method assign is overloaded such away that it corresponds to the most of constructors of the class.