Increase an array index by 1 C#

Question

I have an integer array that I use for counting.

What is the easiest way to increase a certain index of the integer array by 1?

My code looks like this at the moment.

input = Convert.ToInt32(textBox1.Text);
number1 = rand.Next(1, 7);
number2 = rand.Next(1, 7);
number3 = rand.Next(1, 7);

//array used to keep track of how many times a certain number has showed up
int[] counters = new int[14];

int sum = number1 + number2 + number3;

for (int i = 0; i <= input; i++)
{

    counters[sum] = counters[sum] + 1; //counters[sum]++;???
}

for (int i = 0; i < 14; i++)
{
    richTextBox1.Text += "The number " + (i + 1) + "showed up" + counters[i] + " times\n";
}

What am I doing wrong? Why can't I do:

array[i]++;    or     array[i] = array[i] + 1; ???

EDIT for clarity.

What i am trying to do:

roll 3 dices as often as the user wants

sum the 3 dice rolls together (sum should be between 3 -18) and then keep a count of how often each sum showed up.

Then lastly display in % how many times each number showed up.

Answer 1

You can use linq and List to do this, see this code:

input = Convert.ToInt32(textBox1.Text);

for(var i = 0; i < input; i++)
{
    number1 = rand.Next(1, 7);
    number2 = rand.Next(1, 7);
    number3 = rand.Next(1, 7);

    //array used to keep track of how many times a certain number has showed up
    int sum = number1 + number2 + number3;
    sums.Add(sum); //Where sums is a List<int>
}
var report = sums.GroupBy(i => i).Select(g => new { TimesShowedUp = g.Count(), Sum = g.Key });

foreach(var r in report)
{
    richTextBox1.Text += "The number " + r.Sum + "showed up" + r.TimesShowedUp + " times\n";
}

Answer 2

It sounds like what you actually want is the following.

Random rand = new Random();
int numberOfRolls = Convert.ToInt32(textBox1.Text);
int[] counters = new int[16]; //16 different possible sums (3 to 18)

for (int i = 0; i < numberOfRolls; i++)
{
    int sum = rand.Next(1, 7) + rand.Next(1, 7) + rand.Next(1, 7);
    counters[sum - 3]++;
}

for (int i = 0; i < 16; i++)
{
    richTextBox1.Text += "The number " + (i + 3) + " showed up " + counters[i] + " times\n";
}

This take the number of times to roll from textBox1 then loops that number of times creating a sum from the 3 random numbers (1-6). And increments a corresponding position in the array. Since there are 16 possibilities the array is initialed to that size and you just subtract 3 to convert from the sum to the index and then add 3 to convert back when printing.

Answer 3

//array used to keep track of how many times a certain number has showed up
int[] counters = new int[15];

iterations = Convert.ToInt32(textBox1.Text);

for (int i = 1; i <= iterations; i++)
{
    number1 = rand.Next(1, 7);
    number2 = rand.Next(1, 7);
    number3 = rand.Next(1, 7);

    int sum = number1 + number2 + number3;

    counters[sum-3]++;
}

for (int i = 0; i <= 15; i++)
{
    richTextBox1.Text += "The number " + (i + 3) + " showed up " + counters[i] + " times\n";
}