linked list implementation in C

Question

In the following code for a linked list implementation, I am getting the error cannot convert node_type to node * for argument 1 to 'node *insert(node *)'. I don't understand this message. Basically the program is not able to call the function insert from main().

Can anyone help explain this?

#include <stdio.h>
#include <conio.h>
#include <stdlib.h>

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

typedef struct node_type node;

node  *insert(node *head);
void print1(node *temp);

int main(void){
    int dat;
    char x,ch;

    node *temp;


    temp=NULL;
    printf("do u wanna enter a new node? \n");
    scanf("%c", &x);
    if (x=='y' or x=='Y'){

        temp=(node *)malloc(sizeof(node));
        printf("enter the data: \n");
        scanf("%d ", &dat);

        temp->data= dat;
        temp->next = NULL;
    }

    printf("do u want to insert another element?\n");
    scanf("%c ", &ch);
    if( ch=='y' or ch=='Y'){
        insert(temp);
    }
    print1(temp);

    getch();

}
node *insert(node *temp)
{
    int dat;
    char ch1;
    node *newnode;

    newnode=(node *)malloc(sizeof(node));

    printf("enter the data: ");
    scanf("%d", &dat);
    newnode->data=dat;
    newnode->next=temp;
    temp=newnode;

    printf("do u want to insert another element?\n");
    scanf("%c ", &ch1);
    if( ch1=='y' or ch1=='Y'){
        insert(temp);
    }
    else return temp;

}
void print1(node *temp)
{
    int t;

    while(temp!= NULL){
        t= temp->data;
        temp= temp->next;
        printf(" %d ", t);
    }
}

In strict C, the structure definition won't compile. If compiled with a C++ compiler, it will compile. Since you're using <conio.h>, you're probably using MS Visual C++, and I'd guess your code is being compiled as C++ rather than C. — Jonathan Leffler
– Jonathan Leffler, Commented Feb 27, 2014 at 5:23

Lee Duhem · Accepted Answer · 2014-02-27 05:52:51Z

1

A few problems in your code:

The definition of struct node_type
```
struct node_type
{
    int data;
    node_type *next;
};
```
is not right according to C syntax, type node_type does not exist before the typedef struct node_type node; statement.

To fix this, you could

a) define struct node_type like this
```
struct node_type
{
    int data;
    struct node_type *next;
};
```
or

b) use (Thanks @yongzhy)
```
typedef struct node_type
{
    int data;
    struct node_type *next;
};
```
or

c) compile your code with a C++ compiler. (Thanks @JonathanLeffler)
All these
```
if (x=='y' or x=='Y'){
```
should be replaced by
```
if (x=='y' || x=='Y'){
```
or you could just include <iso646.h>, which includes #define or || in it (Thanks @JonathanLeffler),

or you should compile your code with a C++ compiler.

edited Feb 27, 2014 at 5:52

answered Feb 27, 2014 at 5:25

Lee Duhem

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1 Comment

Jonathan Leffler Over a year ago

Or the code should include <iso646.h> so that or etc are handled (defined: #define or || or equivalent).

yongzhy · Accepted Answer · 2014-02-27 05:28:24Z

0

add to @leeduhem

typedef struct node_type
{
    int data;
    struct node_type *next;
} node;

this will void additional line of

typedef struct node_type node;

answered Feb 27, 2014 at 5:28

yongzhy

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