Invalid Operation error

Question

I am getting Invalid Operation Error in following code.

 int m = l_score.Min();

where l_score is int list. Why this would happen ?

Edit: Code

 List<int> l_origin = new List<int>();
 List<int> l_k = new List<int>();
 List<int> l_score = new List<int>();



 for (int i = 0; i < 9; i++)
        {
            if (box_matrix[i, 5] == 0 | box_matrix[i, 5] == 1 | box_matrix[i, 5] == 2)
            {

                for (int k = 1; k < 5; k++)
                {

                    if (box_matrix[i, k] == 0)
                    {
                        int scr = 9;
                        l_origin.Add(box_matrix[i, 0]);
                        l_k.Add(k);
                        scr = score_the_move(box_matrix[i,0],k);
                        l_score.Add(scr);

                    }
                }
            }
        }


        //find the best move
       int m = l_score.Min();
       int min_index =  l_score.IndexOf(m);
       machine_line(l_origin[min_index], l_k[min_index]);
       l_origin.Clear();
       l_k.Clear();
       l_score.Clear();

Can you show how you declared l_score? – prashanth Sep 24 '12 at 01:43 — prashanth, Sep 24 '12 at 01:43

John Woo · Answer 1 · 2012-09-24T02:02:51.303

2

You need to import System.Linq:

using Sytem.Linq;

and then your line will work:

int m = l_score.Min();

I bet you are seeing this error: InvalidOperationException (Sequence contains no elements). It occurs when the list is empty.

edited Sep 24 '12 at 02:02

answered Sep 24 '12 at 01:41

John Woo

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Agreed, `Min()` is enough. I've edited to add the real reason why it doesn't work; `import System.Linq` is missing. – Chris Laplante Sep 24 '12 at 01:50
I have already done that import. some other issue is there. i do not know what. – John Watson Sep 24 '12 at 01:53
1

@JohnWatson therefore, your list is empty. – John Woo Sep 24 '12 at 02:03

D Stanley · Accepted Answer · 2012-09-24T13:04:55.970

2

I'm guessing l_score is empty, which is why you're getting that exception. Look at the message of the exception to get more detail.

edited Sep 24 '12 at 13:04

answered Sep 24 '12 at 01:59

D Stanley

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i checked, your are correct that `l_score` is empty. but why it is not getting populated ? – John Watson Sep 24 '12 at 02:15
Because your code to add an item is never called. Could be a logic error with your if statements or just an edge case scenario. – D Stanley Sep 24 '12 at 02:17

score 1 · Answer 3 · answered Sep 24 '12 at 02:01

1

Invalid operation exception is thrown when the list contents no elements, if you call the .Min() method.

Found this when decompiling IEnumerable:

<exception cref="T:System.InvalidOperationException"><paramref name="source"/> contains no elements.</exception>

answered Sep 24 '12 at 02:01

lahsrah

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i checked, your are correct that `l_score` is empty. but why it is not getting populated ? – John Watson Sep 24 '12 at 02:16
@JohnWatson debug your code, maybe non of your if conditions are being met? – lahsrah Sep 24 '12 at 02:18
Using || will make no difference in this case. – D Stanley Sep 24 '12 at 02:25

Invalid Operation error

3 Answers3