Why am I getting non pointer type error in c++?

Question

I made c++ program to take numbers as input until they input zero and save them as linked list and later on print them, but I can't understand why am I getting these errors.

Here is the code :

#include <iostream>
using namespace std;

struct Node
{
   int data;
   Node* next;
};

int main()
{
   Node* head = NULL, temp1, temp2;
   int data = 1;
   while(data)
   {
      cout<<"Enter number or 0 if you want to end : "<<endl;
      cin>>data;
      temp1 = (Node*)malloc(sizeof(Node));
      temp2 = temp1;
      if(head==NULL)
         head = temp1;
      else
         temp2->next = temp1;
   }
   Node* temp1 = head->next;
   while(temp1->next != NULL)
   {
      cout<<temp1->data<<endl;
      temp1 = temp1 -> next;
   }
       return 0;
   }

I am getting these errors :

test.cpp: In function 'int main()':
test.cpp:18:41: error: no match for 'operator=' (operand types are 'Node' and 'Node*')
       temp1 = (Node*)malloc(sizeof(Node));
                                         ^
test.cpp:4:8: note: candidate: constexpr Node& Node::operator=(const Node&)
 struct Node
        ^~~~
test.cpp:4:8: note:   no known conversion for argument 1 from 'Node*' to 'const Node&'
test.cpp:4:8: note: candidate: constexpr Node& Node::operator=(Node&&)
test.cpp:4:8: note:   no known conversion for argument 1 from 'Node*' to 'Node&&'
test.cpp:21:17: error: cannot convert 'Node' to 'Node*' in assignment
          head = temp1;
                 ^~~~~
test.cpp:23:15: error: base operand of '->' has non-pointer type 'Node'
          temp2->next = temp1;
               ^~
test.cpp:25:10: error: conflicting declaration 'Node* temp1'
    Node* temp1 = head->next;
          ^~~~~
test.cpp:12:23: note: previous declaration as 'Node temp1'
    Node* head = NULL, temp1, temp2;
                       ^~~~~
test.cpp:26:15: error: base operand of '->' has non-pointer type 'Node'
    while(temp1->next != NULL)
               ^~
test.cpp:28:18: error: base operand of '->' has non-pointer type 'Node'
       cout<<temp1->data<<endl;
                  ^~
test.cpp:29:21: error: base operand of '->' has non-pointer type 'Node'
       temp1 = temp1 -> next;
                     ^~

In the line `Node* head = NULL, temp1, temp2;`, the way you positioned the `*` is misleading. Your mistake would be more obvious if you had written that line like this: `Node *head = NULL, temp1, temp2;` — Andreas Wenzel, Oct 05 '20 at 20:21
Big fan of one definition, one line. disk space is cheap and readability is like gold. — user4581301, Oct 05 '20 at 20:24
C++ have is own memory gestion (and prelly good), you don't need to use `malloc`. — DipStax, Oct 05 '20 at 20:24
You should prefer `new` to `malloc`. The operator `new` calls constructions, `malloc` doesn't. — Thomas Matthews, Oct 06 '20 at 00:19

score 0 · Answer 1 · answered Oct 05 '20 at 20:53

This approach would have you append to the beginning of the list... I’d hate to give you the straight answer...but hope this helps !

Allocate the node: W/ new Node()

Insert the user data into the new node’s data var

Have the new node point to the head pointer (new_node->next)

Readjust head pointer to point to new_node (making it the new head)

Why am I getting non pointer type error in c++?

1 Answers1