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2-Dimensional Array issue

Jan 27, 2011 at 6:45pm
RAWBERRY (32)
I'm attempting to build a program to solve a http://projecteuler.net/index.php?section=problems&id=11 Project Euler problem using a 2-dimensional array. I've looked over some of the posts about multidimensional arrays here for help, however, I have run into an error which is somehow causing my program to crash. Here is what I have so far - just filling the 2D array:

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#include <iostream>
using namespace std;

int main()
{
    int n = 0;
    int grid[20][20];
///////////////////////////////////////////////////////////////////////////////////////////
//Number Grid - Visual/////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////////////////
    int list[400] =                                                                      //
    {                                                                                    //
        8, 02, 22, 97, 38, 15, 00, 40, 00, 75, 04, 05, 07, 78, 52, 12, 50, 77, 91, 8,    //
        49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 04, 56, 62, 00,  //
        81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 03, 49, 13, 36, 65,  //
        52, 70, 95, 23, 04, 60, 11, 42, 69, 24, 68, 56, 01, 32, 56, 71, 37, 02, 36, 91,  //
        22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80,  //
        24, 47, 32, 60, 99, 03, 45, 02, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50,
        32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70,
        67, 26, 20, 68, 02, 62, 12, 20, 95, 63, 94, 39, 63, 8, 40, 91, 66, 49, 94, 21,
        24, 55, 58, 05, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72,
        21, 36, 23, 9, 75, 00, 76, 44, 20, 45, 35, 14, 00, 61, 33, 97, 34, 31, 33, 95,
        78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 03, 80, 04, 62, 16, 14, 9, 53, 56, 92,
        16, 39, 05, 42, 96, 35, 31, 47, 55, 58, 88, 24, 00, 17, 54, 24, 36, 29, 85, 57,
        86, 56, 00, 48, 35, 71, 89, 07, 05, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58,
        19, 80, 81, 68, 05, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 04, 89, 55, 40,
        04, 52, 8, 83, 97, 35, 99, 16, 07, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66,
        88, 36, 68, 87, 57, 62, 20, 72, 03, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69,
        04, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 8, 46, 29, 32, 40, 62, 76, 36,
        20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 04, 36, 16,
        20, 73, 35, 29, 78, 31, 90, 01, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 05, 54,
        01, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 01, 89, 19, 67, 48
    };

    //Fill the Grid using the number list
    for (int county = 1; county <= 20; county++)
    {
        for (int countx = 1; countx <= 20; countx++)
        {
            grid[countx][county] = list[n];
            cout << grid[countx][county] << ", ";
            n++;
        }
    }
    return 0;
}
Edit & Run


And here is the output after it crashes:

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8, 2, 22, 97, 38, 15, 0, 40, 0, 75, 4, 5, 7, 78, 52, 12, 50, 77, 91, 8, 49, 49,
99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 4, 56, 62, 0, 81, 49, 31
, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 3, 49, 13, 36, 65, 11, 42, 69,
 24, 68, 56, 1, 32, 56, 71, 37, 2, 36, 91, 22, 31, 16, 71, 51, 67, 63, 89, 41, 9
2, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80, 24, 47, 32, 60, 99, 3, 45, 2, 44, 75,
 33, 53, 78, 36, 84, 20, 35, 17, 12, 50, 32, 98, 81, 28, 64, 23, 67, 10, 26, 38,
 40, 67, 59, 54, 70, 66, 18, 38, 64, 70, 67, 26, 20, 68, 2, 62, 12, 20, 95, 63,
94, 39, 63, 8, 40, 91, 66, 49, 94, 21, 24, 55, 58, 5, 66, 73, 99, 26, 97, 17, 78
, 78, 96, 83, 14, 88, 34, 89, 63, 72, 21, 36, 23, 9, 75, 0, 76, 44, 20, 45, 35,
14, 0, 61, 33, 97, 34, 31, 33, 95, 78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 3, 80
, 4, 62, 16, 14, 9, 53, 56, 92, 16, 39, 5, 42, 96, 35, 31, 47, 55, 58, 88, 24, 0
, 17, 54, 24, 36, 29, 85, 57, 86, 56, 0, 48, 35, 71, 89, 7, 5, 44, 44, 37, 44, 6
0, 21, 58, 51, 54, 17, 58, 19, 80, 81, 68, 5, 94, 47, 69, 28, 73, 92, 13, 86, 52
, 17, 77, 4, 89, 55, 40, 4, 52, 8, 83, 97, 35, 99, 16, 7, 97, 57, 32, 16, 26, 26
, 79, 33, 27, 98, 66, 88, 36, 68, 87, 57, 62, 20, 72, 3, 46, 33, 67, 46, 55, 12,
 32, 63, 93, 53, 69, 4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 8, 46, 29, 3
2, 40, 62, 76, 36, 20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 8
5, 74, 4, 36, 16, 20, 73, 35, 29, 78, 31, 90, 1, 74, 31, 49, 71, 48, 86, 81, 16,
 23, 57, 5, 54, 1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 1, 89
, 19, 67, 48, 2009156344, -1, 2009399844, 2292024, 2009308538, 2009141916,
Process returned -1073740972 (0xC0000354)   execution time : 1.703 s
Press any key to continue.


The array fills correctly all the way up until the last few massive numbers, which I don't have a clue where they originated.
Last edited on Jan 28, 2011 at 6:03pm
Jan 27, 2011 at 11:43pm
aleks0110 (1)
//here is the answer to your problem, works in DEV C++



#include <iostream>
using namespace std;

int main()
{
int n = 0;
int grid[20][20];
///////////////////////////////////////////////////////////////////////////////////////////
//Number Grid - Visual/////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////////////////
int list[400] = //
{ //
8, 02, 22, 97, 38, 15, 00, 40, 00, 75, 04, 05, 07, 78, 52, 12, 50, 77, 91, 8, //
49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 04, 56, 62, 00, //
81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 03, 49, 13, 36, 65, //
52, 70, 95, 23, 04, 60, 11, 42, 69, 24, 68, 56, 01, 32, 56, 71, 37, 02, 36, 91, //
22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80, //
24, 47, 32, 60, 99, 03, 45, 02, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50,
32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70,
67, 26, 20, 68, 02, 62, 12, 20, 95, 63, 94, 39, 63, 8, 40, 91, 66, 49, 94, 21,
24, 55, 58, 05, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72,
21, 36, 23, 9, 75, 00, 76, 44, 20, 45, 35, 14, 00, 61, 33, 97, 34, 31, 33, 95,
78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 03, 80, 04, 62, 16, 14, 9, 53, 56, 92,
16, 39, 05, 42, 96, 35, 31, 47, 55, 58, 88, 24, 00, 17, 54, 24, 36, 29, 85, 57,
86, 56, 00, 48, 35, 71, 89, 07, 05, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58,
19, 80, 81, 68, 05, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 04, 89, 55, 40,
04, 52, 8, 83, 97, 35, 99, 16, 07, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66,
88, 36, 68, 87, 57, 62, 20, 72, 03, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69,
04, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 8, 46, 29, 32, 40, 62, 76, 36,
20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 04, 36, 16,
20, 73, 35, 29, 78, 31, 90, 01, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 05, 54,
01, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 01, 89, 19, 67, 48
};

//Fill the Grid using the number list
for (int county = 0; county < 20; county++)
{
for (int countx = 0; countx < 20; countx++)
{
grid[countx][county] = list[n];
cout << grid[countx][county] << ", ";
n++;
}
}
system ("pause");
return 0;
}
Jan 28, 2011 at 6:01pm
RAWBERRY (32)
Removing the '<=' and replacing it with '<' only fills a 19x19 grid instead of a 20x20. However, because I am starting at 1 instead of at 0 to fill the grid, there were not enough cells because my array was only set for sizes of 20.

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for (int county = 0; county <= 19; county++) //Change the count to 0, and the limit to 19
{
    for (int countx = 0; countx <= 19; countx++)//Change the count to 0, and the limit to 19
    {
        grid[countx][county] = list[n];
        cout << grid[countx][county] << ", ";
        n++;
    }
}


I assume this is because there was no room for the null operator at the end of the array, and the program didn't like that.
Last edited on Jan 28, 2011 at 6:02pm
Jan 28, 2011 at 6:08pm
hanst99 (2869)
aleks is right Rawberry. You declared a 20x20 array. Arrays start with the index 0 and end with the index n-1 in C++. Your program crashed because you tried to access values that were out of range, the weird numbers are values that couldn't be intialized anymore before it crashed.
Last edited on Jan 28, 2011 at 7:37pm
Jan 31, 2011 at 8:15am
RAWBERRY (32)
Aleks' solution filled the 2d array wrong, however, his post led me to figure out the right solution. Thanks for the clarification on the array indexing though.
Jan 31, 2011 at 9:54pm
moorecm (1932)
Just a little tip: prefer using < DIM rather than <= DIM-1 so that the definition of the array and the dimension in the loop correspond.
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