Help with simple program

Prime b

What I'm trying do is to make program show how many times certain number has been generated. For example, if random number = 1 then +1 in the label displayed, if number 1 generated again then +1 to label which equal to 2 now and etc. Same with two and three, but in my case every time i click button , it would just display 1 in different labels and not display the sum of how many times they have been generated.... For each number i have separate label.

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}

private void button1_Click(object sender, EventArgs e)

{

Random gen = new Random();

int number = gen.Next(1, 4);

label5.Text = number.ToString();

if (number == 1)

{

int sum = 0;

int count = 1;

sum += count;

label9.Text = sum.ToString();

}

else if (number == 2)

{

int sum = 0;

int count = 1;

sum += count;

label10.Text = sum.ToString();

}

else if (number == 3)

{

int sum = 0;

int count = 1;

sum += count;

label11.Text = sum.ToString();

}

5 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes14y ago
Accepted answer
Well, the totals array has 3 elements.

The idea is for:

totals[0] to count the occurrences of the number 1,
totals[1] to count the occurrences of the number 2 and
totals[2] to count the occurrences of the number 3

As all arrays start from an index of 0, we therefore have to deduct 1 from number to get the array element we need to count that number.

The ++ operator does the same as it does for a 'scalar' variable; it takes the value of the array element, increases it by one and reassigns it to that array element. So, in other words:

totals[number - 1]++;

does the same as:

totals[number - 1] = totals[number - 1] + 1;
0
Vulpes14y ago
Well, you could create an array with 4 elements corresponding to indices of 0, 1, 2 and 3.

You could then use totals[3] to count the occurrences of the number 3 and so subtracting one would be unnecessary.

However, the trouble with this is that totals[0] would not be used and so you'd be allocating more memory than you need to. Whilst you can argue that this doesn't really matter in a small application, it goes against the grain with most developers - particularly those who remember what programming was like when memory was severely limited and every byte was important.
0
Prime b14y ago
Vulpes i think we dont need to subtract -1 from index, because the random is 1 through 4, 4 is not included, which means there's no need to subtract 1!
:P
0
Prime b14y ago
Vulpes what does totals[number - 1]++ do?

totals is an array [ then it subtracts 1 from the random number] adds one?
0
Vulpes14y ago
What I'd suggest here is that you introduce an array to count the number of times each number has occurred.

I'd also make the Random variable a field rather than a local variable so you don't have to keep recreating a new object each time the button is pressed:

public partial class Form1 : Form
{
private Random gen;
private int[] totals;

public Form1()
{
InitializeComponent();
gen = new Random();
totals = new int[3];
}


private void button1_Click(object sender, EventArgs e)
{
int number = gen.Next(1, 4);

label5.Text = number.ToString();

totals[number - 1]++;

if (number == 1)
{
label9.Text = totals[0].ToString();
}
else if (number == 2)
{
label10.Text = totals[1].ToString();
}
else if (number == 3)
{
label11.Text = totals[2].ToString();
}

}
0