FILE* fp = fopen(argv[1], "r");
if (fp == NULL) {
    printf("Cannot open filen");
    return 1;
}

//Begin copying file using fgetc
int c;
while ((c = fgetc(fp)) != EOF) {
    for (int i = 0; i < PUZZLE_SIZE; ++i) {
        for (int j = 0; j < PUZZLE_SIZE; ++j) {
            if (c != -38) { //-38 is newline
                //puzzle is a global array of ints
                puzzle[i][j] = c - 48; //handles ASCII to int (1-9) conversion
            }
        }
    }
}
fclose(fp);

534678912
672195348
198342567
859761423
426853791
713924856
961537284
287419635
345286179

for (int i = 0; i < PUZZLE_SIZE; ++i)
    for (int j = 0; j < PUZZLE_SIZE; ++j) {
        c = fgetc(fp);
        if (c == 'n')
            c = fgetc(fp); // get a new char if we hit a newline
         puzzle[i][j] = c - `0`;
    }