c++ error: expected type-specifier

Question

When I attempt to compile this simple linked list testing program using the command

g++ -o SLLtest SLLtester.cpp intSLList.o

I receive the error:

SLLtester.cpp: In function ‘int main()’:
SLLtester.cpp:4:27: error: expected type-specifier
SLLtester.cpp:4:27: error: cannot convert ‘int*’ to ‘intSLList*’ in initialization
SLLtester.cpp:4:27: error: expected ‘,’ or ‘;’

I am missing something simple but I am not sure what. The header and the definitions of the linked list compile without a problem. The three files are included.

//intSLList.hh
#ifndef INT_LINKED_LIST
#define INT_LINKED_LIST

class intSLList {
public:
 intSLList(){head=tail=0;}
 void Print();
 void AddToHead(int);
 void AddToTail(int);
 int RemoveFromHead();
 int RemoveFromTail();

protected:
 struct Node {
  int info;
  Node *next;
  Node(int e1, Node *ptr = 0) {info = e1; next = ptr;}
 } *head, *tail, *tmp;
 int e1;
};

#endif

And the definitions:

//intSLList.cpp
#include "intSLList.hh"
#include <iostream>

void intSLList::AddToHead(int e1){
 head = new Node(e1,head);
 if (!tail)
  tail = head;
}

void intSLList::AddToTail(int e1){
 if (tail) {
  tail->next = new Node(e1);
  tail = tail->next;
 }
 else 
  head = tail = new Node(e1);
}

int intSLList::RemoveFromHead(){
 if (head){
  e1 = head->info;
  tmp = head;
  if (head == tail)
   head = tail = 0;
  else 
   head = head->next;
 delete tmp;
 return e1;
 }
 else
  return 0;    
}

int intSLList::RemoveFromTail(){
 if (tail){
  e1 = tail->info;
  if (head == tail){
   delete head;
   head = tail = 0;
  }
  else {
   for ( tmp = head; tmp->next != tail; tmp = tmp->next);
   delete tail;
   tail = tmp;
   tail->next = 0;
  } 
  return e1;
 }
 else return 0;
}

void intSLList::Print(){
 tmp = head;
 while( tmp != tail ){
  std::cout << tmp->info << std::endl;
  tmp = tmp->next;
 }
}

And finally the main function:

#include "intSLList.hh"

int main(){
 intSLList* mylist = new intSLList::intSLList();
 for ( int i = 0; i < 10; i++ ){   
  mylist->AddToTail(i);    
 }
 mylist->Print();
}

Thank you for the help.

Answer 1

intSLList* mylist = new intSLList::intSLList();

This is wrong. When we write new intSLList(), we're not "calling the constructor" — merely naming the type — and therefore naming the constructor in full (as intSLList::intSLList) is flat-out wrong.

So:

intSLList* mylist = new intSLList();

You don't need dynamic allocation here anyway:

#include "intSLList.hh"

int main()
{
   intSLList mylist;

   for (int i = 0; i < 10; i++) {
      mylist.AddToTail(i);    
   }

   mylist.Print();
}

Answer 2

You're trying to call the constructor as a function. The constructor will be called automatically when you allocate the object, so change to

intSLList mylist;

That's it, no need for pointers or dynamic allocation at all.