Array Items In C#

Question

User-256025523 posted

Hi All,

         I have array with 10,000 records with numbers. I have to add all the numbers using C#. Which is the fastest way to perform this operation?

  Thanks,

Prashant N

Answer 1

User-1078128378 posted

Hi,

use  this Method

 private void ArrayAddtion()
        {
            int[] arr = new int[] { 1, 2, 3 };
            int sum = 0;
            sum = arr.Sum();
            Response.Write("sum= " + sum);
        }

and call this method in your button click event like this

 private void button1_Click(object sender, EventArgs e)
        {
            ArrayAddtion();
        }

Thanks,

Answer 2

User-256025523 posted

Thanks Murali !! Let me check this.

Answer 3

User-986267747 posted

Hi pr_nimbalkar,

I have array with 10,000 records with numbers. I have to add all the numbers using C#. Which is the fastest way to perform this operation?

In my experience, if you are use .Net 3.5, you could use the following code:

int sum = arr.Sum();
Console.WriteLine(sum);

If you're not using .NET 3.5 you could do this:

int sum = 0;
Array.ForEach(arr, delegate(int i) { sum += i; });
Console.WriteLine(sum);

Best Regards,

Klein zhang

Answer 4

User-256025523 posted

Thanks !!

Answer 5

User303363814 posted

fastest way to perform this operation?

http://ericlippert.com/2012/12/17/performance-rant/

Answer 6

User-434868552 posted

@pr_nimbalkar

to know what is faster, one must time the code.

based only on my limited testing today, on one million operations, here are my results, fastest to slowest:

1. c.  33":  Array.ForEach(TenK, delegate (int i) { total += i; });
2. c.  40":  for (int index = 0; index < 10000; index++) total += TenK[index];
3. c.  54":  total = TenK.Sum();

The code snippets, shown below, were run in LINQPad 5 on Windows 8.1 intel core i7 16GB RAM

N.B.:  there may be faster methods.

void Main()   // fastest
{
    Int32[] TenK = new Int32[10000];
    for (int index = 0; index < 10000; index++) TenK[index] = index + 1;
    Console.WriteLine((10000 * 10001) / 2); // compute sum of 1, 2, ..., 9999, 10000 using shortcut
    Int32 loops = 1000000;
    DateTime start = DateTime.Now;
    Int32 total = 0;
    for (int outerIndex = 0; outerIndex < loops; outerIndex++)
    {
        total = 0; // re-initialize because we're using +=
        Array.ForEach(TenK, delegate (int i) { total += i; });
    }
    DateTime end = DateTime.Now;
    Console.WriteLine(end - start);
    Console.WriteLine(total);
}

void Main()  // second fastest
{
    Int32[] TenK = new Int32[10000];
    for (int index = 0; index < 10000; index++) TenK[index] = index + 1;
    Console.WriteLine((10000*10001)/2); // compute sum of 1, 2, ..., 9999, 10000 using shortcut
    Int32    loops = 1000000;
    DateTime start = DateTime.Now;
    Int32 total = 0;
    for (int outerIndex = 0; outerIndex < loops; outerIndex++)
    {
        total = 0;   // re-initialize because we're using +=
        for (int index = 0; index < 10000; index++) total += TenK[index];
    }
    DateTime end   = DateTime.Now;
    Console.WriteLine(end - start);
    Console.WriteLine(total);
}

EDIT:

void Main()   // slowest of these 3 examples occurs when using .Sum() method
{
    Int32[] TenK = new Int32[10000];
    for (int index = 0; index < 10000; index++) TenK[index] = index + 1;
    Console.WriteLine((10000 * 10001) / 2); // compute sum of 1, 2, ..., 9999, 10000 using shortcut
    Int32 loops = 1000000;
    DateTime start = DateTime.Now;
    Int32 total = 0;
    for (int outerIndex = 0; outerIndex < loops; outerIndex++)
        total = TenK.Sum();
    DateTime end = DateTime.Now;
    Console.WriteLine(end - start);
    Console.WriteLine(total);
}

purpose of edit:  to fix copy and paste error for the last example.  mea culpa

END EDIT.

Answer 7

User303363814 posted

If you change the statement

TenK[index] = index + 1;

to

TenK[index] = index * 1000 + 1;

Then the answer printed for 'total' is incorrect.

The fastest code which gives the wrong answer is probably

Console.WriteLine(1);

But why ask random people on the internet?  Write the code yourself.  Check the answer is correct.  Time it.