Answer
out = covariance, in = contravariance.
Allows safe substitutability. Includes delegate variance, IEnumerable variance, and array pitfalls.
Quick Answer
Covariance (out T) on interfaces like IEnumerable means IEnumerable is assignable to IEnumerable. Contravariance (in T) on delegates like Action means Action is assignable to Action. These only apply to interfaces and delegates — not concrete generic classes.
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SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
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Source: SugharaIQ