Linked list w/ structure

[5rjK]

http://rafb.net/paste/results/tJoB4z75.html

After executing the following code I receive the errors:
a.c: In function `insert':
a.c:59: error: incompatible types in assignment

I have no problem when first_name in the structure is an int. I can easily assign a default value in the insert function. But I would like to allow full strings to be sent to the field from the insert function....Any ideas?

The code is:

/*Program to illustrate construction of linked list
  Written by Ron
  April 2006

  Language: C (gcc target)
*/



#include <stdio.h>
#include <stdlib.h>   /*malloc is in stdlib, malloc.h not required*/

typedef struct member
  {int number; int id_number; char first_name[30];
   struct member *next;
  }RECORD;

RECORD* insert(RECORD *it, int value); /*Prototype for insert*/
void traverse_and_print(RECORD *head);

int max = 0;
int main(void)
  {
    int i, result, count;
    RECORD *head, *p;
    head=NULL;
    result=1;
    for (i=1; i<=5; i++)
       head=insert(head,i);
/* DRAW PICTURE OF LINKED LIST AT THIS POINT OF PROGRAM*/
    traverse_and_print(head);
    return 0;
  }


RECORD* insert(RECORD *it, int value)
/*Function to insert a record into a linked list
  Written by Ron
  April 2006

  Language: C (Borland 5.01)
*/
{
   RECORD *cur, *q;
   int i; char first_name[30]; char last_name[30];
   //printf("Enter an employee number\n");
   //scanf( "%d", &i );
   //printf("Enter first name\n");
   //scanf( "%s", &first_name );
   //printf("Enter last name\n");
   //scanf( "%s", &last_name );



//   printf("Entering insert, value is %d\n", value);
   cur=(RECORD *)malloc(sizeof(RECORD));
   cur->number=value;
   cur->id_number=i;
   cur->first_name="First Name";

   cur->next=NULL;
   if (it==NULL)
      it=cur;
   else
      {q=it;
       while(q->next!=NULL)
         q=q->next;
       q->next=cur;
      }
   return(it);
}

void traverse_and_print(RECORD *head)
/*Function to traverse linked list, print values in records, and
  mutiply them*/

{ RECORD *p;
  int result;
  result=1;
  p=head;
  while (p!=NULL)
     {result=p->number;
      //printf("num is %d", p->id_number);
      if(result > max){max = result;}
      p=p->next;
     }
  printf("MAX IS %d", max);

  while (p!=NULL)
     {result=p->number;
      //printf("num is %d", p->id_number);
      if(result > max){max = result;}
      p=p->next;
     }


  return;
}

[Tonto]

strcpy(cur->first_name, "First Name");

[vart]

strncpy is better

[5rjK]

I need to find the structure with the smallest id_number. I figured it to find the largest one I could do:

   strcpy(cur->first_name, first_name);
   strcpy(cur->last_name, last_name);

   if(i > max){max = i;post_id=value;}

But I can't figure out how to find the minimum since the function is continously called.

[Tonto]

>> strncpy is better

Dirr -- strcpy is faster!

>> I need to find the structure with the smallest id_number.

I do not understand what you mean. The member of your linked list which has the smallest ID? How does the code you posted illustrate that (finding the max one I guess in the case you posted) and similarly what is post_id.

[vart]

you should initialize your starting min vlue to something big enough to be bigger than any possible value in the list, then your approach will work also for finding min

(you can use something like INT_MAX for example)

[Tonto]

>> you should initialize your starting min vlue to something big enough
>> to be bigger than any possible value in the list, then your approach
>> will work also for finding min
>>
>> (you can use something like INT_MAX for example)

Or you can say (after checking for the case of an empty list) that the min is equal to the first element of the list and then progress through the list reassigning the min if you find a smaller one.

[Dave_Sinkula]

strncpy is better

And potentially more prone to misuse.
http://c-faq.com/lib/strncpy.html

[verbity]

When I look for a min value I like to go opposite of what I do in max...a generic code would be:

minimum = current_i_value;
max = (some ridiculously huge number, within reason);

for(i = max; i > 0; i--)
{
    if(current_i_value < minimum)
          minimum = current_i_value;
}

return minimum;

It seems kinda weird but after you use it twice it makes sense and you'll never screw it up with max due to the decrement operator. But I'm new at this so don't listen to me :-).

[vart]

And potentially more prone to misuse.
http://c-faq.com/lib/strncpy.html

any of suggested alternatives are good for me - all prevent from buffer overrun. That strcpy does not.

[Salem]

Write a 2-line function which wraps around strncpy() and always appends a \0