Question

I need to store in a text file two integers and then the lines of a text. i’ve successfully done it by writing each int in a line and each line of the text in a new line too. In order to read it, however, I’ve found some troubles. I’m doing this:

FILE *f = fopen(arquivo, "r");
char *lna = NULL;
fscanf(f, "%d\n%d\n", &maxCol, &maxLin);
//↑This reads the two ints, works fine in step-by-step
for (;;) {
    fscanf(f, "%s\n", &lna);
    //↑This sets lna to NULL always, even if there are more lines
    if (lna != NULL)
        lna[strlen(lna) - 1] = '\0';
    if (feof(f))
        break;
    inserirApos(lista, lna, &atual);
}
fclose(f);

I’ve tryied a few different ways, but they never worked. I understand I can read everthing like strings, with gets or something, but I think that has a problem if the string contains spaces. I wanted to know if the way I’m doing is the best, and what’s wrong with it. I’ve found one of these methods (that didn’t work either) that you have to pass the maximum length of each line. I know this information if necessary, it’s the maxCol I read before.

Answer 1

fscanf(f, "%s\n", &lna);

Is the wrong argument type. The %s format expects a char* as argument, but you gave it a char**. And you have not allocated memory to that pointer. fscanf expects a char* pointing to a large enough memory area.

char *lna = malloc(whatever_you_need);
...
    fscanf("%s ", lna);

(no difference between the '\n' and ' ' in the fscanf format. both consume the entire whitespace following the string of non-whitespace characters scanned int lna.)