getting an error of undeclared node in compiling a simple linked list program

Question

code

#include <stdio.h>

void main()
{
     struct Node      //defining a node
     {
          int data;             //defining the data member
          struct Node *next;    //defining a pointer to Node type variable
     };

      struct Node *head;        //declaring a pointer variable 'head' to a Node type variable.   
      head=NULL;                //Since the head pointer now points nothing,so initialised with NULL.

      struct Node* temp = (Node*)malloc(sizeof(struct Node));//creating a node and storing its adrs in pointer 'temp'
     (*temp).data=2;          //node's data part is initialised.
     (*temp).next= NULL;    //the node points to nothing initially
     head=temp;             //head is initialised with address of the node,so now it points to the node 

     printf("%d",temp->data);
 }

Do not cast the return of `malloc()`. I think i should keep a template of this comment. :p — Haris, Sep 13 '15 at 09:05
As I am naive in it,would you please elaborate Sir? LinkedListImp.c:14:25: error: ‘Node’ undeclared (first use in this function) struct Node* temp = (Node*)malloc(sizeof(struct Node));//creating a node and storing its adrs in pointer 'temp' ^ LinkedListImp.c:14:25: note: each undeclared identifier is reported only once for each function it appears in LinkedListImp.c:14:30: error: expected expression before ‘)’ token struct Node* temp = (Node*)malloc(sizeof(struct Node));//creating a node and storing its adrs in pointer 'temp' — ABHISHEK KUMAR, Sep 13 '15 at 09:07
The `error` message that you are getting, when you are trying to `compile` — Haris, Sep 13 '15 at 09:08
compiled without typecasting,getting an error: warning: incompatible implicit declaration of built-in function ‘malloc’ [enabled by default] struct Node* temp =malloc(sizeof(struct Node)); — ABHISHEK KUMAR, Sep 13 '15 at 09:11
@ABHISHEKSRIVASTAVA Function `malloc` is defined in this header . — ameyCU, Sep 13 '15 at 09:24
@ameyCU Thanks.Can you site any resource to study about structure and pointers. — ABHISHEK KUMAR, Sep 13 '15 at 09:27
@ABHISHEKSRIVASTAVA For standard reference -http://www.cplusplus.com/reference/ . for working programs -http://www.geeksforgeeks.org/c/. — ameyCU, Sep 13 '15 at 09:33
@ABHISHEKSRIVASTAVA But mainly I found **Stackoverflow** very helpful . Regular visiting and Q & A's are vary helpful. — ameyCU, Sep 13 '15 at 09:34
Please have a look here: http://stackoverflow.com/q/562303/694576 Have your choice(s), read and come back. — alk, Sep 13 '15 at 10:14

score 1 · Answer 1 · edited May 23 '17 at 10:26

1

You should write

struct Node* temp = (struct Node*)malloc(sizeof(struct Node));

instead of

 struct Node* temp = (Node*)malloc(sizeof(struct Node));

because struct tags are in a different namespace than usual identifiers. So the struct keyword is necessary to specify that.Read this

Moreover include <stdlib.h> else you will receive a warning that you are implicitly declaring malloc.

edited May 23 '17 at 10:26

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answered Sep 13 '15 at 09:28

Sourav Kanta

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getting an error of undeclared node in compiling a simple linked list program

1 Answers1