121
What is an expression tree in C#?
An expression tree represents code as a tree-like data structure rather than immediately compiling it into executable instructions.
C# Interview
Advanced LINQ, Expressions & Collections
C# interview questions covering advanced linq, expressions & collections.
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122
What is the difference between Func<T, bool> and Expression<Func<T, bool>>?
Func<T,bool> is a compiled delegate that can execute C# logic directly. Expression<Func<T,bool>> is a data structure representing the lambda expression.
123
What is the difference between ToList(), ToArray(), and AsEnumerable()?
ToList() immediately enumerates a sequence and stores the results in a List<T>. ToArray() also materializes immediately but stores the results in an array.
124
What is materialization in LINQ and Entity Framework Core?
Materialization is the process of executing a query and creating in-memory objects from its results.
125
What is a HashSet<T>, and when should it be used?
HashSet<T> is a generic collection that stores unique values and provides efficient membership checks.
126
What is the difference between Dictionary<TKey,TValue> and ConcurrentDictionary<TKey,TValue>?
Dictionary<TKey,TValue> is a general-purpose key-value collection and is not designed for unsynchronized concurrent writes.
127
What is an IComparer<T> in C#?
IComparer<T> defines custom ordering logic through the Compare method. It is useful when objects need to be sorted using a rule that is separate from the object's natural ordering.
128
What is IEqualityComparer<T> in C#?
IEqualityComparer<T> defines custom equality and hash-code logic for a type without changing the type itself.
129
What are immutable collections in .NET?
Immutable collections create a new collection when a change is requested rather than modifying the existing instance.
130
What is the difference between IEnumerable<T>, IReadOnlyCollection<T>, and IReadOnlyList<T>?
IEnumerable<T> guarantees only that a sequence can be enumerated.