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AnswerRe: Exceptions Pin
lmoelleb18-Jan-22 20:40
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GeneralRe: Exceptions Pin
Eddy Vluggen19-Jan-22 0:40
professionalEddy Vluggen19-Jan-22 0:40 
GeneralRe: Exceptions Pin
lmoelleb19-Jan-22 0:48
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GeneralRe: Exceptions Pin
Eddy Vluggen19-Jan-22 1:12
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AnswerRe: Exceptions Pin
Eddy Vluggen18-Jan-22 18:02
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AnswerRe: Exceptions Pin
jschell23-Jan-22 7:32
Memberjschell23-Jan-22 7:32 
Questionnecessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
BillWoodruff16-Jan-22 2:39
mveBillWoodruff16-Jan-22 2:39 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
harold aptroot16-Jan-22 3:21
Memberharold aptroot16-Jan-22 3:21 
There is no way to do it in general, not even in theory.

TryGetNonEnumeratedCount is neat, but only actually outputs the count when it is called on a collection that knows its count. For general enumerables such as WhereListIterator, it returns false. So OK, it doesn't evaluate the enumerable, but it also doesn't help.

Any on a WhereListIterator has to evaluate until it finds an element or runs out of input. There's nothing else it could do. BTW Any includes TryGetNonEnumeratedCount-like tricks, examining the type of the object it is called on, and if it is an ICollection then it just checks whether its count is zero (there are additional details but they don't help here either), but those tricks cannot apply to a filtered enumerable.

If there was any method that could in general predict whether a filtered enumerable is going to have anything in it (without iterating through it), that would have strange implications. It would act as a powerful oracle (of the theoretical computer science variety) that can extract information from a black box function without ever actually evaluating the function. Spooky.
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
BillWoodruff16-Jan-22 5:14
mveBillWoodruff16-Jan-22 5:14 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
harold aptroot16-Jan-22 6:56
Memberharold aptroot16-Jan-22 6:56 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
BillWoodruff16-Jan-22 18:22
mveBillWoodruff16-Jan-22 18:22 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
Richard Deeming16-Jan-22 22:45
mveRichard Deeming16-Jan-22 22:45 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
BillWoodruff18-Jan-22 1:19
mveBillWoodruff18-Jan-22 1:19 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
Richard Deeming18-Jan-22 1:41
mveRichard Deeming18-Jan-22 1:41 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
BillWoodruff18-Jan-22 3:08
mveBillWoodruff18-Jan-22 3:08 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
Richard Deeming18-Jan-22 6:17
mveRichard Deeming18-Jan-22 6:17 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
BillWoodruff19-Jan-22 13:58
mveBillWoodruff19-Jan-22 13:58 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
Richard Deeming19-Jan-22 21:43
mveRichard Deeming19-Jan-22 21:43 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
BillWoodruff20-Jan-22 4:26
mveBillWoodruff20-Jan-22 4:26 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
harold aptroot16-Jan-22 22:48
Memberharold aptroot16-Jan-22 22:48 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
BillWoodruff18-Jan-22 0:49
mveBillWoodruff18-Jan-22 0:49 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
jschell23-Jan-22 7:40
Memberjschell23-Jan-22 7:40 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
BillWoodruff25-Jan-22 3:58
mveBillWoodruff25-Jan-22 3:58 
GeneralRe: necessity to use .Any() to check if an IEnumerable<T> result has no items without iterating over it ? Pin
jschell30-Jan-22 6:22
Memberjschell30-Jan-22 6:22 
QuestionRemove a page from pdf document in C# Pin
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