CODEWITHSUNDEEP
c#arraysfor-loop
bnr32jason
bnr32jason

Reputation: 113

Array not displaying properly

This is homework assignment for school, but I'm begging for someone to just correct my code. I've been working at this for two days and I think I have everything worked out except I can't get it to work as a 2D Array, so I set this up temporarily just to try to figure things out, but I'm digging myself deeper into a hole I think.

The assignment requires that two dice be rolled 36,000 times and then the results for each sum be displayed on the right, and the sum of the two dice on the left, like this in a 2D array:

12 850
11 1020
10 1200
...
2 900

I've got the right column displaying correctly, but the left column won't display the sums, it just displays "System.Int32[]" a bunch of times.

Here's the code:

Random rand = new Random();
const int ARRAY_SIZE = 13;
const double DICE_ROLLS = 36000;
int sum = 0;
int die1 = 0;
int die2 = 0;

int[] sums = new int[ARRAY_SIZE];

int[] dice = { 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};

for (int i = 0; i < DICE_ROLLS; i++ )
{
    die1 = rand.Next(1, 7);
    die2 = rand.Next(1, 7);

    sum = die1 + die2;
    sums[sum] += 1;
}

for (int i = 2; i < sums.Length; i++)
{
    Console.WriteLine("{0,2}      {1,8}", dice, sums[i]);
}

Upvotes: 0

Views: 195

Answers (2)

Sani Huttunen
Sani Huttunen

Reputation: 24385

Since you'll be using a 2d array you'll want to do something like this:

var rand = new Random();
const double diceRolls = 36000;

var sums = new[,] {{2, 0}, {3, 0}, {4, 0}, {5, 0}, {6, 0}, {7, 0}, {8, 0}, {9, 0}, {10, 0}, {11, 0}, {12, 0}};

for (var i = 0; i < diceRolls; i++)
{
  var die1 = rand.Next(1, 7);
  var die2 = rand.Next(1, 7);

  var sum = die1 + die2;
  sums[sum - 2, 1] += 1;
}

for (var i = 0; i < sums.GetLength(0); i++)
{
  Console.WriteLine("{0,2}      {1,8}", sums[i, 0], sums[i, 1]);
}

Note 1: sum - 2. Since the array length is only 11 you need to subtract 2 from the dice value. (0-10 instead of 2-12).

Note 2: sums.GetLength(0). If you use sums.Length you'll get 22 since there actually are 22 elements in the array. You need to get the length for rank 0

Note 3: Since you're dealing with 2d arrays you'll have the sum of the dice roll in sum[i, 0] and the total count in sum[i, 1].

Upvotes: 1

Peter Duniho
Peter Duniho

Reputation: 70671

In the spirit of the homework assignment, rather than fixing the code outright, I will try to explain the parts you need to fix, and let you do the actual fixing.

The primary issue in your code is that you are trying to print dice as the value for the left column of the output, rather than individual elements of dice (e.g. dice[i]).

Note, however, that you can't just use dice[i], because your dice array has fewer elements in it than the sums array. If you just replaced dice with dice[i] in your WriteLine() statement, you'd get an index-out-of-bounds exception.

IMHO, the best way to address this is to initialize sums with 11 elements instead of 13, and then when tracking the sums (i.e. in your first loop), subtract 2 from the actual sum value to get the index for the sums array:

sums[sum - 2] += 1;

Then in your second loop, you can safely just use i to index both arrays.

I hope that helps. Please feel free to ask for any clarifications and good luck with your assignment.

Upvotes: 3

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