Reading A Text File Into A Linked List

[Edved]

I am trying to read in a text file and add strings from it word by word into a Linked List. I'm fairly new at C and don't quite understand pointers. I've had a few different errors just messing around with it, but now I'm getting an infinite loop within my main program.

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

struct listNode {  /* self-referential structure */
   char data[50];
   struct listNode *nextPtr;
};

typedef struct listNode LISTNODE;
typedef LISTNODE *LISTNODEPTR;

void insert(LISTNODEPTR *, char[]);
char delete(LISTNODEPTR *, char[]);
void printList(LISTNODEPTR);
int fpeek(FILE *);

main() {

    FILE *fptr;
    char file_name[20];
    int nrchar = 0;
    LISTNODEPTR startPtr = (struct listNode *) malloc(sizeof(struct listNode));
    startPtr->nextPtr = NULL;
    char word[50];
    char c;
    int i;

    printf("What is the name of the file in which the text is stored?\n");
    scanf("%s",file_name);
    //    printf("Type the number of characters per line");
    //scanf("%d", &nrchar);
    fptr = fopen(file_name,"r");
          while(fpeek(fptr) != EOF) {
      i = 0;
      while(fpeek(fptr) != ' '){
        word[i] = fgetc(fptr);
        i++;
        printf("%d",i);
      }
      word[i] = '\0';
      insert(&startPtr, word);
      printf("%c", word[4]);
      
       }
    fclose(fptr);
    printList(startPtr);
    

return 0;
}

    /* Insert a new value into the list in sorted order */
    void insert(LISTNODEPTR *sPtr, char value[])
    {
      LISTNODEPTR newPtr, currentPtr;

      newPtr = malloc(sizeof(LISTNODE));
      strcpy(newPtr->data, value);
      newPtr->nextPtr = NULL;
      currentPtr = *sPtr;

      while(currentPtr && currentPtr->nextPtr){
        currentPtr = currentPtr->nextPtr;
      }
      currentPtr->nextPtr = newPtr;
       
    }


    /* Return 1 if the list is empty, 0 otherwise */
    int isEmpty(LISTNODEPTR sPtr)
    {
       return sPtr == NULL;
    }

    /* Print the list */
    void printList(LISTNODEPTR currentPtr)
    {
       if (currentPtr == NULL)
          printf("List is empty.\n\n");
       else {
          printf("The list is:\n");

          while (currentPtr != NULL) {
             printf("%s --> ", currentPtr->data);
             currentPtr = currentPtr->nextPtr;
          }

          printf("EOF\n\n");
       }
    }

    int fpeek(FILE *stream) {
        int c;
        c = fgetc(stream);
        ungetc(c, stream);
        return c;
    }

When I run my full code, it prints 12345ooooooooooooooooooooooo...etc. In my test file the first word is "Hello" so that's where the infinite 'o's come from. If the outer loop is the one that is infinite, then wouldn't the second while loop also execute more than once? What I mean is, why is the second print statement the only one that repeats itself?

[tabstop]

So what happens when fpeek(fptr) does in fact equal a space? The outer condition is still true (space is not EOF), the inner condition will always be false (since you don't have a way to get past the space), so the outer loop spins endlessly while the inner loop can never start. You need to clear that space (easiest way is to read it in out of the file) so that you can move on to the next word.

(The real fun will start if you don't have a space after your last word....)

[Edved]

Why doesn't the fpeek function check the next character after the space? Is there a better function to use for reading in characters from a file so that I wouldn't have to worry about clearing the space?

[camel-man]

Its getting put back into the stream when you call ungetc, ultimately keeping the character there I believe.

Edit: you could say something like this to move along the character.

while(fpeek(fptr) != ' '){
        word[i] = fgetc(fptr);
        i++;
        printf("%d",i);
      }
if(fpeek(fptr))==' ')
char garbage = fgetc(fptr);

[Edved]

Thank you, using the garbage variable along with adding another check for EOF in the second loop made it work.

[vart]

I do not understand need in fpeek at all - as if you are trying not to read some characters from file?.. You need to read all and store only some parts...
So read all and then decide what to do

int ch;
while((ch = fgetc(f)) != EOF)
{
   if(isspace(ch))
   {
     /* word ended - store it, if it contains something */
   }
   else
  {
      word[i] = ch; 
      i++;
   }
}
/* here store the last word if file was not properly ended with \n */