“No matching function for call to X” Error in C++

Question

I'm trying to add a new object to a vector of objects of a class called Vertex, which has a constructor like this:

Vertex::Vertex(int x)
{
  index=x;
  next=NULL;
  entry_time=0;
  exit_time=0;
  connections=0;
}

However, I think I can't put information directly into the vector,and believe I have to previously create an object of class Vertex, ascribe to it the information I want, and then add it to the vector by using

Graph::Graph(bool x, int y)
{
  is_digraph=x;
  order=y;
  is_connected=false;
  for(int i=0; i<order; i++)
  {
    Vertex vt(i+1);
    v.push_back(vt);
  }
}

But the error "no matching function for call to 'Vertex::Vertex()'" keeps popping up, as if I sent no integer as argument, even though I'm pretty sure that by declaring the object as "Vertex vt(i+1)" I'm sending an integer as the argument. What is my mistake?

Answer 1

A vector requires that the type being stored has a default (no arg) constructor. This is necessary so that things like creating a vector with an initial known number of elements works. Your Vertex doesn't have a default constructor to it is not suitable to be put in a vector "as is".