Question

I’m trying to read a map from a text file and create a string array according to the number of rows and columns in the map. Every cell in the grid is a 2 character string.

For instance,

**--**--**--
--**--**--**

should create a 2*6 matrix. The number of rows and columns are ROWS and COLS respectively. I used

char ***map = malloc(ROWS * sizeof(char *));
for (i = 0; i < ROWS; i++) 
{
    map[i] = malloc(COLS * sizeof(char) *  2);
}

But when I try to use a map[x][y], it will segfault.

Answer 1

char ***map; could be interpreted as an “Array of arrays of strings”, so the inner array actually contains char pointers. Therefore, your loop needs to look like this:

for(i = 0; i < ROWS; i++) {
    int j;

    map[i] = malloc(COLS * sizeof(char*));
    for(j = 0; j < COLS; j++) map[i][j] = malloc(3 * sizeof(char)); // 3 chars because a string has to be terminated by \0
}

Alternatively, you could declare map as char **map, then your initialization code would work, but then you’d need to use map[i][j] and map[i][j+1] to access the elements of the individual cells.