How to get a specific index in multidimensional Array C#

Question

I have a two-dimensional array, object[,] mData

I need to retrieve the index of a specific string (key) in that object array without using a loop (e.g foreach, for).

The reason why I don't want to use a loop is because I am trying to optimize a current block of code that uses a loop which causes the process to take a long time since it is managing too much data.

Is there a way to do this?

CODE

`

object [,] mData = null;  
string sKey = String.Empty;  

for (int iIndex = 0; iIndex < mData.GetUpperBound(1); iIndex++)  
{  
    if (mData[0, iIndex].Value == sKey);  
    {
       return;  
    }  
}

`

Perhaps show your loop because it maybe that we can identify how to speed it up — BugFinder, Nov 28 '16 at 13:19
If you need a specific element, use `array2d[0][0]` (firstmost element). Otherwise, you have to use loops for mudane arrays. — devRicher, Nov 28 '16 at 13:19
You might reconcider creating an index on top of your array. Something that is sorted which can be binary searched. — Jeroen van Langen, Nov 28 '16 at 13:35
Hi @BugFinder, I have modified my question to include the code. I hope that helps. — user2775418, Nov 29 '16 at 01:39
Like Stefano said, why not a dictionary? That seems to do exactly what you need. Check out this: http://stackoverflow.com/a/5742863/2321042 — Andrew, Nov 29 '16 at 01:45
Hi @StefanoM5, May I ask if you can give an example? Thank you. — user2775418, Nov 29 '16 at 02:05
@user2775418, if you search you will find plenty of examples, like this one: https://www.dotnetperls.com/dictionary — Andrew, Nov 29 '16 at 02:38
Please note the following. Use right [order](http://stackoverflow.com/q/9936132/5045688) of the loops to eliminate cache miss. Try to use [sentinel value](https://en.wikipedia.org/wiki/Sentinel_value). After all, use the parallelization. — Alexander Petrov, Nov 29 '16 at 05:40

score 0 · Answer 1 · answered Nov 28 '16 at 13:32

You will need a loop to linear search for an element. Even if there is a method that you can call to get the index (which there isn't, I don't think), there would still be a loop inside the method.

If you're worried about performance, try a binary search if the data is sorted.

I am trying to optimize a current block of code that uses a loop which causes the process to take a long time since it is managing too many data.

Loops don't neccessarily make your code run significantly slower. The core of your problem is that you have too many data. If you have that many data, then slowness is expected. What you can do is to run the time-consuming operation asynchronously so that the UI doesn't freeze.

How to get a specific index in multidimensional Array C#

1 Answers1