How to fscanf a file into a linkedlist?

Question

so i have a file that consist of integers. And i would like to use fscanf to read the file's integers into a linkedlist. But during the compile time, the function just wait there for an input(as if there is a scanf somewhere in the function). Please Help me :(

Code

struct Node{
int data;
struct Node *next;
};

typedef struct Node Node;



void fillListFromFile(Node **head)
{
    FILE *f;
    if((f=fopen("/home/fileOints001.txt","r"))==NULL)
        printf("You cannot open");
    Node *newNode = malloc(sizeof(Node));
    while(fscanf(f, "%d", &(newNode->data)))
    {
    newNode->next = *head;
    *head = newNode;
    Node *newNode = malloc(sizeof(Node));

    }

}



fillListFromFile(&head); // in the main

Answer 1

Your loop only ends if it fails to convert the input (ie fscanf() will return 0 here). But you do not check for EOF . Thus, you spin your wheels trying to read over and over. Something like:

int rc;

/* ... */

while ((rc = fscanf(...)) && rc != EOF) {
    /* ... */
}

This way you check for the end of file condition, and terminate the loop when you hit it.

Answer 2

You need some error checking to make sure that your file parses correctly and the like.

Also, it may be a good idea not to allocate a node before its data has been successfully read.

typedef struct Node {
    int data;
    struct Node *next;
} Node;

Node* fillListFromFile()
{
    FILE *f;
    if(!(f = fopen("/home/fileOints001.txt","r"))) {
        perror("/home/fileOints001.txt");
        abort();
    }

    Node *head = NULL, **tail = &head, *node;
    int n;
    while(1 == fscanf(f, "%d", &n)) {
        // allocate a new node
        node = malloc(sizeof(Node));
        if(!node) {
            fprintf(stderr, "failed to allocate memory");
            abort();
        }

        // and append it to the list
        node->data = n;
        node->next = NULL;
        *tail = node;
        tail = &node->next;
    }
    if(!feof(f)) {
            fprintf(stderr, "failed to parse the file");
            abort();
    }

    return head;
}