Question

I’m trying to take words from a text file to a linked list.

FILE *f = fopen("test.txt","r");
     while (fgets( line, sizeof(line), f ))
       for (word = strtok(line, " "); word; word = strtok(NULL, " "))
         {
            temp->data=word;
            temp->next=(node *) malloc(sizeof(node));
            printf("%s\n",word); // this prints the words correctly
            temp=temp->next;
         }

But when I list the words from the beginning of the linked list, they are incorrect. I think its about strtok?

Answer 1

You’re reading lines of your file into a single buffer that gets reused for each line — line.

strtok returns a pointer into the buffer it operates on.

You store the result of strtok into your linked list without making a copy of the string.

When you read the next line, that pointer still points at the same place in the line, but now there’s different data in that line. You won’t get what you expect.

To fix it you need to copy (with strcpy or something similar) the result into a buffer in your linked list. If you have strdup available, you might want to use that.