CODEWITHSUNDEEP
cpointers
Hank
Hank

Reputation: 231

Passing pointer to other .c file as a parameter

I want to use insertion() from inside LinkedList.c. I am not able to pass the pointer into insertion.h file from another file.

error: head->data I am getting the below error: "pointer to incomplete class type is not allowed Node *head"

Insertion.h

#include <stdio.h>
extern void insertion(struct Node *head)
{
   printf("\n value present at head: %d", head->next->data);
   printf("\nvalue of head %d\n", head);

}

LinkedList.c

#include <stdio.h>
#include "inserttion.h"

struct Node
{
   int data; //size of int is 4
   struct Node *next;
};

int main()
{
struct Node *head = NULL;
struct Node *second = NULL; //size of second is 8
struct Node *third = NULL;

int option;

head = (struct Node *)malloc(sizeof(struct Node));
second = (struct Node *)malloc(sizeof(struct Node));
third = (struct Node *)malloc(sizeof(struct Node));

head->data = 1;
head->next = second;

second->data = 2;
second->next = third;

third->data = 3;
third->next = NULL;

insertion(head);

return 0;
}

I am new to C, pls let me know if I am missing something.

Upvotes: 0

Views: 894

Answers (1)

Some programmer dude
Some programmer dude

Reputation: 409166

The other file you use, Insertion.h, should not be a header file. Instead it should be a source file.

You should still have a header file, but it should contain the structure instead. And both source files should include that header file.

Something like

Insertion.h

#pragma once

struct Node
{
   int data; //size of int is 4
   struct Node *next;
};

Insertion.c

#include <stdio.h>
#include "Insertion.h"

void insertion(struct Node *head)
{
   if (head != NULL && head->next != NULL)
       printf("\n value present at head->next: %d", head->next->data);

   printf("\nvalue of head %p\n", (void *) head);
}

Main.c

#include <stdio.h>
#include "Insertion.h"

int main(void)
{
    ...
}

The you build and link the two source files, and both will know of the structure.

Also note that I have added null-pointer checks for the pointers before you dereference them. And changed the printf format specifier used to print the pointer.

Upvotes: 3

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