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home / developersection / interviews / what is covariance and contravariance in c#?
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What is covariance and contravariance in C#?

Ponu Maurya 434 23 Jun 2025
c# c#
Updated 23 Jun 2025
Ponu Maurya
Ponu Maurya

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Ponu Maurya
Ponu Maurya 23 Jun 2025
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Answer:

Covariance and contravariance allow you to use a more derived or more base type than originally specified.

  • Covariance (out): Enables method to return a more derived type.
  • Contravariance (in): Allows passing a less derived type as an argument.
IEnumerable<string> strings = new List<string>(); // covariance
Action<object> act = (o) => Console.WriteLine(o); 
Action<string> strAct = act; // contravariance (invalid in this case)

Applies to generic interfaces and delegates.

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