c# - When can IEnumerable not be converted to IList? -

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i found code in project i'm working on:

ienumerable<int> foo = ienumerableintvariable ilist<int> ?? ienumerableintvariable.tolist();

i know as returns null if can't convert, , tolist() kick in finish job, situations in happen?

among others, consider simple case:

public ienumerable<int> getlistofnumbers() {     (int = 0; < 100; i++)         yield return i; }

this returns true ienumerable wouldn't implement ilist (msdn). clearly, adding/removing "collection" doesn't make sense, nor elements accessible via index.


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