c# - Sequence contains no elements -

can explain me why following linq query throws invalidoperationexception?
(don't list has no elements,the value i'm looking exists in collection)

class program {      static int lastnumber;      static void main()      {           int loopcount = 100; int minvalue = 1; int maxvalue = 10000;           var numbers = enumerable.range(minvalue, maxvalue).tolist();//or toarray();           random random = new random();            (int = 0; < loopcount; i++)           {               //.first() throws exception obvious value exists in list               int x = numbers.where(v => v == newmethod(minvalue, maxvalue, random)).first();           }           console.writeline("finished");           console.readline();       }       private static int newmethod(int minvalue, int maxvalue, random random)      {          var a1 = random.next(minvalue + 1, maxvalue - 1);          lastnumber = a1;          return a1;      } } 

the problem appears when call newmethod inside lambda expession.
if works

int temp=newmethod(minvalue, maxvalue, random); int x = numbers.where(v => v == temp).first(); 

i added lastnumber field debug code,you can see value exists in collection when crashes

ps
problem not random variable,i removed parameter , create new local random inside method problem still exists

update

it turns out don't need loop make crash. if run program many times error again

using system; using system.collections.generic; using system.diagnostics; using system.linq; class program {     static int lastnumber;     static void main()     {         int minvalue = 1, maxvalue = 100000;         var numbers = enumerable.range(minvalue, maxvalue).toarray();         //crashes         int x = numbers.where(v => v == newmethod(minvalue, maxvalue)).first();         console.writeline("finished");         console.readline();      }       private static int newmethod(int minvalue, int maxvalue)      {           random random = new random();           var a1 = random.next(minvalue + 1, maxvalue - 1);           lastnumber = a1;           return a1;       }  } 

@oleg right, here's why it's problem.

where scans through list looking elements match given criteria. in case the criteria changes each element. if made problem smaller, array of 5 elements:

list<int32> (5 items) 1  2  3  4  5  

and looped through looking value matches random number (x item[i] , r random number):

item 1: x = 1, r = 2  // fail item 2: x = 2, r = 3  // fail item 3: x = 3, r = 2  // fail item 4: x = 4, r = 3  // fail item 5: x = 5, r = 2  // fail 

note no item match particular random number, no item matched criteria , first throws exception!

the fix, have discovered, generate random number before enumeration:

int temp=newmethod(minvalue, maxvalue, random);  // 2  item 1: x = 1, temp = 2  // fail item 2: x = 2, temp = 2  // success! 

side note:

it's bit misleading use maxvalue here:

 enumerable.range(minvalue, maxvalue) 

since second parameter enumerable.range length of resulting collection, not max value. in case works because you're starting @ 1 results unexpected if used, 99 , 100 - you'd range 99 198.