Thread: explain me the error in this linked list creation program

Code:

#include<stdio.h>
#include<stdlib.h>
struct node{
int data;
struct node *next;
};
void ins(struct node *temp,struct node *head)
{
  temp->next=head;
head=temp;                #error caused by this line
}
void main()
{
struct node *head,*temp,*p;
char c;
int i;
printf("Do you want to enter data? Y/N ");
scanf("%c",&c);
fflush(stdin);
if(c=='y'||c=='Y')
{
head=(struct node *)malloc(sizeof(struct node));
printf("enter your data: ");
scanf("%d",&i);
fflush(stdin);
head->data=I;
head->next=NULL;
printf("Do you want to enter more data? Y/N ");
scanf("%c",&c);
fflush(stdin);
}
while(c=='y'||c=='Y')
{
temp=(struct node *)malloc(sizeof(struct node));
printf("enter your data: ");
scanf("%d",&i);
fflush(stdin);
temp->data=i;
temp->next=NULL;
ins(temp,head);
printf("Do you want to enter more data? Y/N ");
scanf("%c",&c);
fflush(stdin);
}
p=head;
while(p!=NULL)
{
printf("%d ",p->data);
p=p->next;
}
}

If I cut "head=temp" line from ins function definition and paste it after ins function call, this program works smoothly but why it is not working good in this above condition? please explain!!

Please properly indent your code so it's readable: Indent style - Wikipedia, the free encyclopedia

In the mean time, a few other things to read:

FAQ > Why fflush(stdin) is wrong - Cprogramming.com
FAQ > main() / void main() / int main() / int main(void) / int main(int argc, char *argv[]) - Cprogramming.com
FAQ > Casting malloc - Cprogramming.com

Well the part which is causing error is different!

Re-post the code with proper indentation.

any one else who can reply and help?

Originally Posted by gaurav#

any one else who can reply and help?

Ignoring advice makes me less likely to help you. Posting crappy looking code might make others less likely to help you.

I'll give you some help this time, but if you continue to make it difficult for us to help you (by not posting neat-looking code), then don't count on continued help from me.

For starters, you don't initialize any of your pointers. So if the user does not enter 'y' or 'Y', you attempt to access random memory in your last "while()" loop.

Your "ins()" function is all wrong. First of all, you're assigning "head" to "temp->next", which means it's no longer the head. Then you try assign temp back to head (which won't work anyway; to change the value of *head, you need to pass a pointer to *head to the function). But this is still not the right approach.

Try this. In your "ins()" function, declare a node pointer. Assign the value of head to this pointer. Use this node pointer to traverse the list until you get to the last valid node. Then assign "temp" to "node->next".