Read line by line into linked list

Question

I want to put each line in a text file in a node in a linked list. I have managed to write out the text line by line, but when I try to store the line in a node, only the last line of the text is saved in all the nodes. Any idea what I'm doing wrong?

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

struct list
{
    char *line;
    struct list *next;
};

int main(void)
{
    FILE *f;
    f = fopen("text.txt", "r");
    if (f == NULL) exit("ERROR\n");

    struct list n1, n2, n3, n4;
    struct list *pointer = &n1;

        n1.line = NULL;
        n1.next = &n2;
        n2.line = NULL;
        n2.next = &n3;
        n3.line = NULL;
        n3.next = &n4;
        n4.line = NULL;
        n4.next = 0;

    int nodenr = 0;

    int buf[50];
    while(fgets(buf, sizeof(buf), f) != NULL)
    {
        printf("%s", buf);
        ++nodenr;
        if (nodenr == 1)
        {
            n1.line = buf;
        }
        else if (nodenr == 2)
        {
            n2.line = buf;
        }
        else if (nodenr == 3)
        {
            n3.line = buf;
        }
        else if (nodenr == 4)
        {
            n4.line = buf;
        }
    }

    while (pointer != 0)
    {
        printf("%s\n", pointer->line);
        pointer = pointer->next;
    }
    fclose(f);
}

Answer 1

Your problem occurs because all your nodes' line pointer point to the buf buffer, so all will have the last line you read into it.

You have to assign a copy of the buffer for each node when you read it, not the buffer pointer itself.