linq - What's more efficient in .Any and .Count in C# (Extension methods) -

this question has answer here:

• which method performs better: .any() vs .count() > 0? 7 answers

public void methodname(observablecollection<datacollection> datacollection)     {         if (datacollection != null)         {             ischecked = datacollection.any(o => o.datacollectionid.equals(30));              ischecked = datacollection.where(o => o.datacollectionid.equals(30)).count() > 0;         }                 } 

can explain me, efficient way use above 2 filtering? .any? or .where.count?

note: consider datacollection has on 10,000 items.

please advice me. thank you

reviewing framework... depends. initial instincts in hypothetical-land:

any() checks see if there single value. if so, returns true. o(1) operation.

count() have either 1 of following:

1) access running tally of items in collection, or 2) count items in collection

in best case (#1) operation o(1). in worst, (#2), it's o(n).

in reality, any() uses collection's iterator determine if there next value. so, collection whether or not any() o(1) operation. if poor implementation, possibly o(n).

for example, let's array iterator stupid, , looks first non-null value. has examine each item in array, , therefore any() in case means o(n). (in fact, any() returns true array of length > 1).

count() attempts see if collection implements icollection or icollection<t>, , if so, returns count property's value. if underlying implementation keeps running tab, o(1). if not, o(n) worst case.

if enumerable doesn't implement 1 of interfaces, count() iterates entire collection, counting on way. that's o(n).

tl;dr: according implementation, any() more faster count().