Going blind can't see my error, please help.

Hey guys I just started coding in C, so i'm no up to par with everything. I've been writing a program that deals with structs and linked lists, and I've run into an "imcompatible type in assignment" error and I can't see what's going on because I've been looking at this code for 1.5 hrs now. please help me. Thanks!

here's my func file

Code:

---

#include <stdio.h>
#include <stdlib.h>
#include "funcs.h"


LIST_ELEM *add(LIST_ELEM *pHead,char type[],char name[], char title[], int year, int price, int size){

        LIST_ELEM *new_elem = malloc(sizeof(LIST_ELEM));

        new_elem->type = type;
        new_elem->name = name;
        new_elem->title = title;

        new_elem->year = year;
        new_elem->price = price;
        new_elem->size = size;

        return new_elem;

}

---

my header

Code:

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typedef struct list_elem
{
        char type[5];
        char name[50];
        char title[50];
        int year;
        int price;
        int size;
        struct list_elem *pNext;
}LIST_ELEM;

LIST_ELEM *add(LIST_ELEM *pHead,char type[],char name[], char title[], int year, int price, int size);
int size(LIST_ELEM *phead);
LIST_ELEM *find(LIST_ELEM *pHead, int value);
void print(LIST_ELEM *pHead);

---

and my main (its a noob program, but i'm a noob so its ok :) )

Code:

---

#include <stdio.h>
#include <stdlib.h>
#include "funcs.h"

int main(void){

  LIST_ELEM *pHead = NULL;
  char type[5];
  char name[50];
  char title[50];
  int year;
  int price;
  int size;

  int choice;

  do {
        printf("What would you like to do? \n\n");
        printf("0. Exit \n");
        printf("1. Print books/cds. \n");
        scanf("%d", &choice);

        switch(choice){
          case 1:
                  print(pHead);
                break;
          case 2:
                printf("Enter 'book' or 'cd' for type: \n");
                scanf("%s", &type);
                printf("Enter name of author/artist: \n");
                scanf("%s", &name);
                printf("Enter title: \n");
                scanf("%s", &title);
                printf("Enter year published/released: \n");
                scanf("%d", &year);
                printf("Enter price: \n");
                scanf("%d", &price);
                printf("Size of book/cd: \n");
                scanf("%d", &size);

                pHead = add(pHead,type,name,title,year,price,size);
                break;
               
                        }
                }while(choice != 0);
        return 0;
}

---

I know it has to do with the passing in of character string for my add() method, but I don't know what the right syntax is to get it to work. Thanks again!

You can't copy strings with "=" (as in new_elem->type = type), you must use strcpy.

The problem is when you're attempting to fill your struct...

new_elem->type = type

The string array type is passed to your function as a pointer only. You want to save the contents of that string... so use

strcpy(new_elem->type, type)

... which moves the actual characters.... Hopefully the destination array sizes are always large enough to accommodate the user's input. This is a common "bug", when an evil user (aren't they all?) writes and writes and writes, and causes your program to overshoot the destination array.

THnx that worked. But now when I run it, and enter a title thats bigger then 7 letters it skips one or two of the following printfs. Am i experiencing the whole overshooting the destination array? How would i fix that? I set my char array to be [50] but that didn't work.

It's called a header file. Yes, it's a good idea to include that whenever you use any string functions.

Sorry I edited but it didn't work.

When I type in a string of size larger then 7 letters it skips a couple printfs.

so say for title i put in : the cat and the hat

it jumps over the author and goes right to the publish date. But it doesn't make sense since i allocate sizes of 50 for the title and 50 for the author.

But five characters works fine? Are you sure you don't have %7s or something like that in your program?

yeah pretty sure.

if i put in

name: heres myname

its skips down to date published:

but when i do a print out of it
i get

name: heres
title: name

Yeah I can't replicate the "skipping printfs" at all. I did notice that the new_elem->pNext is not being updated... to link the malloced elements together. But that's not the issue at the moment.

No wait.... if I enter in anything which has spaces in it, the scanf absorbs it into the numbers.... I should have seen that coming. It's late in the day.

Quote:

---

Originally Posted by TaiL

yeah pretty sure.

if i put in

name: heres myname

its skips down to date published:

but when i do a print out of it
i get

name: heres
title: name

---

Ha ha! It's not five characters -- it's the space. %s stops at any whitespace (spaces, tabs, or enter key). To read the whole line, use fgets.

(Note to reader: Ha ha! must be given your best over-dramatic villain interpretation.)

thanks. for that one. Interesting how you don't get the skipping printfs.

No I do.... sort of. They go flying by real fast because their associated inputs are already satisfied. No waiting at the keyboard for those.

Not too sure with fgets

from what i can understand fgets takes in a (str,int, file);

but in my case i don't have a file so can I leave file blank?

Your file is stdin.

so instead of

Code:

---

printf("Enter title: ");
scanf("%s", &title);

---

i do

Code:

---

printf("Enter title: ");
fgets(&title,50, stdin);

---

so then I don't have to declare the size of the char array at the beginning of my file then?

Of course you still have to declare the size of the array.

LOL. This is lot harder then I thought. One problem after the other.

changing my code to this

Code:

---

printf("Enter 'book' or 'cd' for type: ");
fgets(type,5,stdin);

printf("Enter name of author/artist: ");
fgets(name,50,stdin);
               
printf("Enter title: ");
fgets(title,50,stdin);

---

does not allow me to input anything. So when i run i get this:

Code:

---

Enter 'book' or 'cd' for type: Enter name of author/artist:

---

So: mixing scanf and fgets is always ... interesting. scanf leaves the enter-key behind (remember that it stops on whitespace) which means that the first fgets after a scanf doesn't see any input. If you search here you'll see several suggestions for dealing with that. (You can change all your scanf's into fgets, but that gets rather annoying for ints; or you can do an extra read.)

:confused:

whats an extra read?

Quote:

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Originally Posted by TaiL

:confused:

whats an extra read?

---

A read that is extra?

Code:

---

fgets(type, 5, stdin); //an extra read that chomps the newline
fgets(type, 5, stdin);

---

OMG WONDERFUL!!!!! IT WORKS!!!

*HUGS* (in a non weird kind of way)

Thanks a million man!!!

special thanks to tabstop and nonoob. You can archive this forum no mr. moderator. Thanks again. I go now and eat (haven't ate all since lunch). Good night.

And once again THANK YOU!!!!