CODEWITHSUNDEEP
c++multidimensional-array
Jota_sk
Jota_sk

Reputation: 169

Confused about 2D arrays in C++

I'm having problems with creating a 2D boolean array in C++. I wrote a quick program for create and print all the bool array.

#include <iostream>

using namespace std;

int main() {

    const int WIDTH = 20;
    const int HEIGHT = 20;

    bool world [HEIGHT][WIDTH];

    for(int i = 0; i < HEIGHT; i++){
        for(int j = 0; j < WIDTH; j++){
            world[i][j] = true;
        }
    }

    for(int i = 0; i < HEIGHT; i++){
        for(int j = 0; j < WIDTH; j++){
            if(world[i][j]){
                cout << j;
            }else{
                cout << ' ';
            };
        }
        cout << "-" << i << endl;
    }

    return 0;

}

And this is his output.

012345678910111213141516171819-0
012345678910111213141516171819-1
012345678910111213141516171819-2
012345678910111213141516171819-3
012345678910111213141516171819-4
012345678910111213141516171819-5
012345678910111213141516171819-6
012345678910111213141516171819-7
012345678910111213141516171819-8
012345678910111213141516171819-9
012345678910111213141516171819-10
012345678910111213141516171819-11
012345678910111213141516171819-12
012345678910111213141516171819-13
012345678910111213141516171819-14
012345678910111213141516171819-15
012345678910111213141516171819-16
012345678910111213141516171819-17
012345678910111213141516171819-18
012345678910111213141516171819-19

It creates a 2D array, set all his values to true, and print the array. This is fine, the problem is when the 2d array get bigger. For example if I change the size of WIDTH and HEIGHT to 30, when i print the array I have the following ouput:

01234567891011121314151617181920212223242526272829-0
01234567891011121314151617181920212223242526272829-1
01234567891011121314151617181920212223242526272829-2
01234567891011121314151617181920212223242526272829-3
01234567891011121314151617181920212223242526272829-4
01234567891011121314151617181920212223242526272829-5
01234567891011121314151617181920212223242526272829-6
01234567891011121314151617181920212223242526272829-7
01234567891011121314151617181920212223242526272829-8
01234567891011121314151617181920212223242526272829-9
01234567891011121314151617181920212223242526272829-10
01234567891011121314151617181920212201234567891011121314151617181920212223242526272829-11
01234567891011121314151617181920212223242526272829-12
01234567891011121314151617181920212223242526272829-13
01234567891011121314151617181920212223242526272829-14
01234567891011121314151617181920212223242526272829-15
01234567891011121314151617181920212223242526272829-16
01234567891011121314151617181920212223242526272829-17
01234567891011121314151617181920212223242526272829-18
01234567891011121314151617181920212223242526272829-19
01234567891011121314151617181920212223242526272829-20
01234567891011121314151617181920212223242526272829-21
01234567891011121314151617181920212223242526272829-22
01234567891011121314151617181920212223242526272829-23
01234567891011121314151617181920212223242526272829-24
01234567891011121314151617181920212223242526272829-25
01234567891011121314151617181920212223242526272829-26
01234567891011121314151617181920212223242526272829-27
01234567891011121314151617181920212223242526272829-28
01234567891011121314151617181920212223242526272829-29

As you can see on the line 11 it counts until 22 and restart the for loop for j. I don't know what is wrong, I need an 2D array of bools of size [50][50] but I don't what is wrong there.

EDIT: The problem is the compiler. I tried the same code on GCC compiler on a Linux machine and works perfectly. This code works fine, the problem is the compiler or the compiler with the CLion IDE. It compiles but I have problems with the running or the output produced. The code works fine with GCC compiler or on an Unix machine

Upvotes: 0

Views: 239

Answers (2)

Aisha Javed
Aisha Javed

Reputation: 169

Okay this is logically absolutely correct and i have tested your code on online compiler using 20 as well as 30. restart your compiler or try another compiler a reliable one... Here is the screenshot of your result when i executed your code online.

enter image description here enter image description here

Upvotes: 2

Ed Heal
Ed Heal

Reputation: 59997

The line

bool world [WIDTH][HEIGHT];

Should be 

bool world [HEIGHT][WIDTH];

As the i in your loop ranges from 0 to HEIGHT-1. j ranges from 0 to WIDTH-1

Upvotes: 1

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