Problem reading in Text File

I am reading in a file and storing its information into this structure:

Code:

---

typedef struct Item
{
  char *name;
  int area;
  struct Item *nextPtr;
} Item;

typedef Item *Ptr;

---

The text file looks like this:

Code:

---

Bread
0
Toast
1
Butter
0

---

...with the name of the item followed by the location of the item in integer form.


I am getting the information from the text file into the structure like so:

Code:

---

void loadItems(Ptr *sPtr)
{
  FILE *file;
  char stuff[30];
  char area[10];
  Ptr newPtr;

  if((file = fopen("items.txt", "r")) == NULL)
  {
      perror("items.txt");
      exit(1);
  }

  while(1)
  {
      if(fgets(stuff, 30, file) == NULL)
      {
        break;
      }
      stuff[strlen(stuff) - 1] = '\0';

      newPtr = malloc(sizeof(Ptr));

      if(newPtr != NULL)
      {
        newPtr->name = stuff;
        sscanf(area, "%d", &newPtr->area);
      }

---

I didn't include all of the code in this function for simplicity's sake (please let me know if more code would be helpful.

MY QUESTION IS...

When reading in the file, the fgets at the beginning of the while loop still reads in the numbers, even though the sscanf at the end of while loop reads them in as well. Is there any way I can get the fgets to skip the numbers? I figured the sscanf would bump the fgets to the next word, but I guess I was wrong...hopefully that makes sense and isn't too convoluted!

A couple of problems:

1. Do not typedef pointers, you have been told that before. It is extremely poor programming practice.
2. You stuff array is local to your function and goes out of scope when your function exits. Thus leaving your node pointing to invalid memory.
3. Why would sscanf effect where your file pointer was. You have it reading from your area buffer, which you never put anything into, and then outputting into your area value of your node. How does that change the file pointer? Here is sscanf explanation.

Code:

---

typedef struct Item
{
    char *name;
    int area;
    struct Item *nextPtr;
} Item;

typedef Item *Ptr;

...

Ptr newPtr;

...

newPtr = malloc(sizeof(Ptr));

---

That certainly doesn't look right... you mean sizeof(*newPtr) instead?

@Andrew, the typedef pointer is actually coming straight from my textbook (C: How to Program by Deitel). While that does not make this decision any better, I am trying to follow the examples as best as possible from the book (the mistakes are all mine, though, haha). I am fully intent on taking your advice in the future.

Is there any way I could replace the sscanf with an fgets, or will fgets not be able to store the number into an integer variable? Is there any way I could bump the file pointer forward otherwise?

Quote:

---

Originally Posted by voidpain()

Is there any way I could replace the sscanf with an fgets, or will fgets not be able to store the number into an integer variable? Is there any way I could bump the file pointer forward otherwise?

---

I am not sure of your file layout, however normally you would just read the file in line by line using fgets into some buffer and then break that up with sscanf() to effectively parse the line. So something like this:

Code:

---

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

struct myNode{
        char name[30]; //note this isn't a pointer
        int number;
};

//just used to make our file
void createFile(void);

int main(void){

        //used for file line input
        char inputBuffer[100]={0};
        FILE* myFile;
        int current=0;
       
        //I am using an array but this would be your linked list
        struct myNode myNodeArray[5];
        //---------------------
       
        //just makes our file to read in
        createFile();
       
        //open our file
        myFile = fopen("example.txt", "r");
       
        if(myFile){
                //read our file in line by line
                while(fgets(inputBuffer, sizeof(inputBuffer), myFile) && current < 5){
                        //break up our line into our structure
                        sscanf(inputBuffer,"%s %d", myNodeArray[current].name, &myNodeArray[current].number);
                        current++;
                }
                fclose(myFile);
        }
        //printf our results
        for(int i = 0; i < current; i++){
                printf("%s %d\n", myNodeArray[i].name , myNodeArray[i].number);
        }

        getchar();
        return (0);
}
void createFile(){

        FILE* myfile = fopen("example.txt", "w");
        if(myfile){
                fprintf(myfile, "John 30\n");
                fprintf(myfile, "Joe 20\n");
                fprintf(myfile, "Bob 15\n");
                fclose(myfile);
        }
}

---

Quote:

---

Originally Posted by voidpain()

Is there any way I could replace the sscanf with an fgets, or will fgets not be able to store the number into an integer variable? Is there any way I could bump the file pointer forward otherwise?

---

Maybe you would find fscanf() more useful.

Awesome, fscanf() worked nicely, thanks!

Thanks Andrew, I'm trying the things in your code in a different file right now

Also, I would like to note that unless there is any reason your files need to be human readable, e.g. txt files, you really should look at just making binary files for this. I am assuming you are making something of a game here, so in that case it would greatly simplify how you manages these files and load your data.

Just search this forum and the internet for "Random Access Files". By doing this you will have many advantages such as reading and writing directly from/to a structure and being able to jump around in your data file, hence "random access".