Question

I’m learning C and I decided to make a text game as my learning project. So I’m trying this primitive “parser” that reads a text file into a 2D array, but there’s a problem: this map doesn’t use 1 character-wide cells, it uses 2 character-wide cells. For instance, the player is represented with a **, a door is represented like ## and so on.

That means, I need to read 2 characters of the text file and then assign it to the respective cell in the map.

Well, I made a test file that contains

aabbccddee
ffgghhiijj
kkllmmnnoo
ppqqrrsstt
uuvvwwxxyy

And I tried to read it with

#include <stdio.h>

#define ROWS 5 
#define COLS 5

int main() {
    FILE *mapfile = fopen("durr", "r");
    char charbuffer[3], row, col, *map[ROWS][COLS];

    /* Initializing array */
    for (row = 0; row < ROWS; row++) {
        for (col = 0; col < COLS; col++) {
            map[row][col] = "  ";
        }
    }

    /* Reading file into array */
    for (row = 0; row < ROWS; row++) {
        for (col = 0; col < COLS; col++) {
            map[row][col] = fgets(charbuffer, 3, mapfile);
        }
    }

    /* Printing array */
    for (row = 0; row < ROWS; row++) {
        for (col = 0; col < COLS; col++) {
            printf("%s", map[row][col]);
        }
        printf("\n");
    }

    fclose(mapfile);    
    return 0;
}

But when I execute it, I get this

uuuuuuuuuu
uuuuuuuuuu
uuuuuuuuuu
uuuuuuuuuu
uuuuuuuuuu

I think it has something to do with the fact that fgets return a pointer, but I’m not sure. I tried doing it with fgetc but it looks messy and I dropped it after reading about gets.

Answer 1

You should have strdup’ed the contents read from the file. Replace the file reading block with this:

/* Reading file into array */
for (row = 0; row < ROWS; row++) {
    for (col = 0; col < COLS; col++) {
        if (fgets(charbuffer, 3, mapfile))
            map[row][col] = strdup(charbuffer);
    }
}

and don’t forget to put this at the beginning of your code too:

#include <string.h>