Thread: Program keeps crashing; attempting to extract each string (word) from text file

I am trying to write a program that will extract each string(word) from a text file and insert it into a linked list. The problem is my program keeps crashing and I cannot figure out why. I believe it is my insert method but I am not sure. Thanks!

Code:

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


struct node
{
  char *data;
  struct node *next;
};


void insertNode(struct node**, char *);
void printList(struct node*);


int main()
{
  struct node *head = NULL;
  FILE *fptr;
  char file_name[20];
  char str[1000];
  int numOfChar;


  printf("Enter the name of the file: ");
  scanf("%s",file_name);


  printf("Enter the number of characters per line: ");
  scanf("%d",&numOfChar);


  fptr=fopen(file_name,"r");


  while(fgets(str, sizeof str, fptr) != NULL)
  {
    int nitems = fscanf(fptr, "%999s", str);


    while (nitems == 1)
    {
        insertNode(&head, str);
        nitems = fscanf(fptr, "%999s", str);
    }


  }


  fclose(fptr);
  printList(head);


  return 0;
}


void insertNode(struct node** nodeHead, char *data)
{
    struct node* new_node = (struct node*) malloc(sizeof(struct node));
    struct node *last = *nodeHead;
    char *str;


    str= (char *)malloc(60*sizeof(char));
    strcpy(str, data);


    new_node->data  = str;
    new_node->next = NULL;


    if (*nodeHead == NULL)
    {
       *nodeHead = new_node;
       return;
    }


    while (last->next != NULL)
    {
        last = last->next;
    }


    last->next = new_node;
}


void printList(struct node* node)
{
    while(node != NULL)
    {
        printf(" %s ", node->data);
        node = node->next;
    }
}

The input is an ASCll text file that contains the following information:

The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into
the actual Service of the United States; he may require the Opinion, in writing, of the principal
Officer in each of the executive Departments, upon any subject relating to the Duties of their respective Offices,
and he shall have Power to Grant Reprieves and Pardons for Offenses against The United States, except in Cases of Impeachment.

The code compiles on my machine without the parentheses on sizeof. I added the parentheses and it still crashes. I am using the Code::Blocks IDE which includes the GNU GCC compiler. I have no idea what is causing it to crash.

Originally Posted by kmdv

Unfortunately, I was unable to reproduce the problem. Line 37 has sizeof without parentheses, so it does not compile as it is. However, I fixed it (added parentheses) and the program runs fine displaying all text from the linked list (in Debug as well as in Release configuration).

Considering error at line 37, are you sure the code posted above is the same you have currently on your machine?

sizeof is not a function call. It's an operator. It doesn't need parentheses. The parentheses that are sometimes necessary are actually the cast operator.

Code:

int x;
size_t s1 = sizeof x;
size_t s2 = sizeof (int);

ok thanks for your help

Does anyone else have any ideas/suggestions/advice or a reason for why it is crashing?

Originally Posted by blongnec

ok thanks for your help

So you thank a guy that can't help you but don't bother thanking me for helping you in your other thread?
F you, buddy!
(I see what's wrong with your program, btw.)

haha calm down. I forgot you even responded. I always appreciate any help that I can get.

Will my program work correctly if i use sscanf? I have used a bunch of different functions to try and read in each word but my program still crashes. I am new to C so bear with me. Thanks for your help.