Question

I am trying to populate a two dimensional array (mapLayout) with chars from a text file.

When I use printf to output the chars as they are being read everything looks fine, however the actual line that adds the char to the array seems to be causing a crash.

#include <stdio.h>
#include <stdlib.h>

void createMap();

//height of file being read
int mapHeight, mapWidth = 20;
char mapLayout[20][20];

int main()
{
    createMap();
    return 0;
}

//read in string from file and populate mapLayout with chars
void createMap(){
    FILE *file = fopen("map.txt", "r");
    int col, row = 0;
    int c;

    if (file == NULL)
        return NULL; //could not open file

    while ((c = fgetc(file)) != EOF)
    {
        printf("%c", c);
        printf("\nx:%d, y:%d\n", col, row);

        if(c == '\n'){
            row++;
            col = 0;
        }else{
            mapLayout[col][row] = c;        //<--  This line seems to be the problem
            col++;
        }

    }

    return;
}

The file I am reading is a 20 x 20 representation of a map. Here it is:

xxxxxxxxxxxxxxxxxxxx
xA                 x
x                  x
x                  x
xxxxxxxxxxxxxxxx   x
x                  x
x                  x
x                  x
x                  x
x                  x
x    xxxxxxxxxxxxxxx
x           x      x
x           x      x
x           x      x
x           x      x
x           x      x
x     xxxxxxx      x
x                  x
x                 Bx
xxxxxxxxxxxxxxxxxxxx

Any help would be greatly appreciated.

Answer 1

int col, row = 0; why col is not initialized to zero. If the first character in the file is \n then it will not crash, for all remaining cases crash will happen (undefined behaviour).

Do

int col = 0;
int row = 0;