CODEWITHSUNDEEP
c++arraysmultidimensional-array
LuukV
LuukV

Reputation: 203

2D array changes multiple values while only one changed

My question is much like this one Setting a value in a 2d array causes others in array to change, however it does not solve what I have here.

I am also trying to make a game field with a 2D array, currently full of '#'. I am trying to get the top left corner to become '.' (but leaving a border or '#' around the field, so its 1, not [0][0]).

However, whatever I tried so far always turns two spots into '.':

################.###
#.##################
####################
#####D##############
####################
####################
####################
####################
####################
####################
####################
####################
####################
####################
####################

This doesn't make any sense, since (as far as I can see) I am not overflowing anywhere into a RAM slot, and even when I set map[1][1].symbol = '.'; it still gives those two spots as '.', though there is only one location being changed.

Code (partial):

#include <ctime>
#include "stdlib.h"

// Create structure for map tiles
struct mapTile{
    char symbol;
    bool walkable;
};

//Set map Width and Height and create empty array
//I did it like this so I can change the width and height later via ingame menu
int const mapWidth = 20;
int const mapHeight = 15;

mapTile map[mapWidth][mapHeight];

char x = 1;
char y = 1;

void generateField(){
    srand(time(NULL)); //not used yet
    //Set whole field to '#'
    for(int y = 0; y < mapHeight; y++){
        for(int x=0; x < mapWidth; x++){
            map[y][x].symbol = '#';
            map[y][x].walkable = false;
        }
    }
    //Open up route to walk


    map[3][5].symbol = 'D';
    map[y][x].symbol = '.';
    map[y][x].walkable = true;

};

void printField(){
    //print each symbol of the field
    for(int y = 0; y < mapHeight; y++){
        for(int x=0; x < mapWidth; x++){
            cout << map[y][x].symbol;
        }
        cout << endl;
    }
}

Upvotes: 1

Views: 330

Answers (2)

Abhinav Arora
Abhinav Arora

Reputation: 537

first of all you are going out of the bounds of the array. The limit of your array is [mapWidth][mapHeight]. But in the initialization loop you are iterating the [y][x] - y till mapHeight and x till mapWidth.

And the second reason is, the value of x and y has already changed when you are initializing it to '.' and false. Please see the array size and work accordingly.

Upvotes: 2

Jonas
Jonas

Reputation: 7017

In both your for-loops you access the map as [height][width], however you define it as [width][height].

Changing it solves the problem (on my machine).

Upvotes: 4

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