Question

I have a table like this;

01 01 02 00 01 02 00 01
01 02 00 01 02 00 01 02
02 00 11 04 04 04 04 04
00 01 10 03 03 03 03 03

I am reading this file like this:

FILE *map = open_file("lazy.map");
if (map == 0)
    return 0;

for (i = 0; i < TOTAL_TILES; ++i) {
    int ttype;
    fscanf(map,"%i",&ttype);
    // do other stuff here...
}

Is there a way that I can check if fscanf failed or not?

Answer 1

Check the return value.

Another option is to use %n format:

int n = -1;
int ttype;
fscanf(map, "%i%n", &ttype, &n);
if(-1 == n)
    // failed to parse

This way you can check how many symbols have been consumed by fscanf. It doesn’t make difference in the above, but in:

int count = fscanf(map, "%i abc %n", &ttype, &n);

count may be greater than one even if abc part of the format didn’t match. On the other hand, n will be set only if the whole format matched.