c++ primer第五版 ３１７页练习２

#include <iostream>
#include <string>
#include <vector>
#include <deque>
#include <list>
#include <forward_list>
#include <string>
#include <array>
using namespace std;
#define LENGTH  10
typedef  int TYPE;
typedef  forward_list<TYPE> FORWARD_LISTTYPE;
void print(FORWARD_LISTTYPE & );
int main()
{
  forward_list<int> fint{1,2,3,4,5,6,6,7,7,8,9,9,10,11};
  forward_list<int>::iterator it = fint.begin(),pre = fint.before_begin();
  while(it != fint.end())
    {
      if(*it % 2)
	{
             it =  fint.insert_after(pre,*it);
             pre = it;
	     ++ pre;
	     ++it;
	     ++it;	     
	}
      else
	{
          it = fint.erase_after(pre);
	   
        }

    }
  print(fint);
  return 0;
}
void print(FORW