Finding the value in an array & its index.

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Hi all,

Can anybody tell me how to look for value in an array with similar elements or different & its index in the array & compare it with a array containing indices's of other data. Like for Ex:

In array1[6] = {1,0,0,1,0,2,0} here i need to check whether the array contains 1s in it & extract the index of 1s in the array. In this example we can see that the array contains 1s & their indices's are 0 & 4. I have got another array which contains the indices's of other data i.e., array2[2] = {2,5}. So here i need to compare indices's of array1 with the data of array2 if both are same some event will be triggered if not some other event.

Thanks in advance.

Posted 25-Apr-13 22:06pm

Jagadisha_Ingenious

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2 solutions

Solution 1

Arrays are sooo last century...

But seriously, you might want to put the indices in HashSet[^]s and then perform set operations on them.

Posted 25-Apr-13 22:28pm

PIEBALDconsult

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Jagadisha_Ingenious 26-Apr-13 4:53am

Hi PIEBALDconsult, actually what i require is i am saving the data in an array & the array is updated everytime & this updated data if it contains the same value in the same position i should not perform any task. If not equal perform some task.

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OriginalGriff · Accepted Answer · 2013-04-25T22:47:00

Solution 2

IT's not difficult to do, but the "normal" methods to speed it up don't work - you can't use Linq because it works on unordered sets, so it has no concept of "index". But the "brute force and ignorance" approach is pretty simple anyway:

C#

int[] myArray = { 1, 0, 0, 1, 0, 2, 0 };
int[] match = { 2, 5 };
List<int> indexes = new List<int>();
for (int i = 0; i < myArray.Length; i++)
    {
    if (myArray[i] == 1) indexes.Add(i);
    }
if (Enumerable.SequenceEqual(indexes, match))
    {
    Console.WriteLine("They match");
    }

Posted 25-Apr-13 22:47pm

OriginalGriff

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Jagadisha_Ingenious 26-Apr-13 5:28am

Hi @OriginalGriff: i get this type of error in the line8 of the code you have posted i am using visual studio 2010 with .net framework 4.0v. So can you tell me how to overcome this error.
"The type arguments for method 'System.Linq.Enumerable.SequenceEqual<tsource>(System.Collections.Generic.IEnumerable<tsource>, System.Collections.Generic.IEnumerable<tsource>)' cannot be inferred from the usage. Try specifying the type arguments explicitly."

OriginalGriff 26-Apr-13 5:46am

Look at how you defined the two arrays (indexes and match in my case) - I'm betting you didn;t specify the type of one of them!