Missing something in my C# count for integers code

Question

I'm doing some excercises for school and ran into a problem. When I try to count the characters in a array it just gives back the array itself. Can anyone tell me what I'm missing? The code is in C#.

public static int CountFor(int n)
{
        int count = 0;

        int[] a = new int[] {n};
        for (int i = 0; i < a.Length; i++)
        {
            count += i;
        }
        return count;
}

and in the main to show the results:

Console.WriteLine(CountFor(1024));
Console.ReadKey();

Visual Studio has a built-in debugger which works faster, more accurate and more satisfying than posting on Stack Overflow. Place a breakpoint (F9) and step through your code (F10) and inspect your variables to see what your code is doing. The code `a = new int[] {n}` is not doing what you expect it to, which is the root cause of your issue. By inspecting it, you could have falsified your problem statement of _"it just gives back the array itself"_, which it doesn't. — CodeCaster, Jan 12 '15 at 11:57

Soner Gönül · Accepted Answer · 2015-01-12T12:27:51.517

5

Change

new int[] {n}

to

new int[n]

With new int[] {n}, you have an array with 1 element as n.

Read: Arrays Tutorial

You can easily use Enumerable.Range and Enumerable.Sum methods to simplify your method like;

public static int CountFor(int n)
{
   return Enumerable.Range(1, n).Sum();
}

edited Jan 12 '15 at 12:27

answered Jan 12 '15 at 11:55

Soner Gönül

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But the console gives back 523776 while it's supposed to give back 4 as 1024 contains 4 integers. Can you explain this? – Johan Wijts Jan 12 '15 at 12:00
2

@Johan your code adds `1+2+3+...+1024`. You can find this out for yourself by using the debugger. If you want to count the number of digits in an integer, that's a different question, which is answered in [How can I get a count of the total number of digits in a number?](http://stackoverflow.com/questions/4483886/how-can-i-get-a-count-of-the-total-number-of-digits-in-a-number). – CodeCaster Jan 12 '15 at 12:00
Thanks again, I can figure the rest out myself like this. – Johan Wijts Jan 12 '15 at 12:04

score 1 · Answer 2 · answered Jan 12 '15 at 11:56

1

You need to use new int[n], otherwise you are generating a new array with length 1 with the passed integer as the content of the array

answered Jan 12 '15 at 11:56

Jcl

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Missing something in my C# count for integers code

2 Answers2