Findindex Method in System.Generics.List

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Hi,
I need to find a index of Object/item stored in List<string>.
It contains about 250 items.

I used List<t>.findindex method, but i am not able to use Predicate delegate.
I have read many articles but i am not able to understand it.

Please help me finding the item in List<string>.

Here is piece of code.

System.Collections.Generic.List<string> AllRanks = new List<string>();

It contains eg:
1. ABC
2. BBC

Thanks in advance.

Posted 15-May-11 23:00pm

prathameshpitale

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3 solutions

Solution 1

How come you did not see it in System.Collections.Generic.List?
Look:
http://msdn.microsoft.com/en-us/library/6sh2ey19(v=VS.100).aspx[^].

You will find a lot of methods including ready-to-use IndexOf (three overloads).

Ahh— predicate… sorry, now I see.

What's the problem about the code sample here:
http://msdn.microsoft.com/en-us/library/x1xzf2ca.aspx[^]?

—SA

Posted 15-May-11 23:16pm

Sergey Alexandrovich Kryukov

Comments

prathameshpitale 16-May-11 5:20am

I Saw the links before Questioning on this forum.. I have mentioned there i am not able to understand the given methods in example...

Can you help me understand the codE?

Sergey Alexandrovich Kryukov 16-May-11 5:36am

How can I help you? By writing another piece of code? You won't understand it either.
(However, see the sample by Debojyoti Majumder. Any better?)
Maybe you need to learn about 1) generics, 2) delegates, looks at more simple examples first?
--SA

prathameshpitale 16-May-11 6:14am

Thanx!

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Sergey Alexandrovich Kryukov · Accepted Answer · 2011-05-15T23:47:00

Solution 3

Better code would be using anonymous method:

C#

System.Collections.Generic.List<string> list =
    new System.Collections.Generic.List<string>();

//...

int index = list.FindIndex(new System.Predicate<string>(
    (value) => {
        return value == "ABC" || value == "BBC";
}));

—SA

Posted 15-May-11 23:47pm

Sergey Alexandrovich Kryukov

Comments

prathameshpitale 16-May-11 6:14am

Thanx!

Sergey Alexandrovich Kryukov 16-May-11 6:23am

You're very welcome.
Thanks for accepting this answer.
Good luck, call again.
--SA

Albin Abel 16-May-11 6:34am

My 5

Sergey Alexandrovich Kryukov 16-May-11 6:43am

Thank you, Albin.
--SA

Debojyoti Majumder · Accepted Answer · 2011-05-15T23:30:00

Solution 2

C#

private static bool Findlogic(string item)
{
 if(item == "ABC" || item == "BBC")
    return true;
 else
    return false
}

then add you code like

C#

int i = AllRanks.FindIndex(Findlogic);

"i" will give you desired index.

Posted 15-May-11 23:30pm

Debojyoti Majumder

Updated 15-May-11 23:37pm

v2

Comments

Sergey Alexandrovich Kryukov 16-May-11 5:39am

Correct, but... I voted 3 for quite ridiculous "if".
Should be: "return item == "ABC" || item == "BBC";" (!)
(I also fixed your formatting and added missing ";")
--SA

prathameshpitale 16-May-11 5:40am

Hey thanks. but can you explain me this ?

Albin Abel 16-May-11 6:34am

My 5