Generic constraints (where clause) in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a generic class with a constraint that T must be a class.

C Sharp (C#)

public class Repository<[1]> where T : class { }

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AT

BU

CV

DK

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different letter in the constraint than in the generic declaration.

Forgetting to add the where clause after the generic declaration.

The generic type parameter is usually named T. The constraint where T : class means T must be a reference type.

2fill in blank

medium

Complete the code to declare a generic method with a constraint that T must have a parameterless constructor.

C Sharp (C#)

public void CreateInstance<[1]>() where T : new() { T obj = new T(); }

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AU

BT

CV

DK

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different letter in the constraint than in the method declaration.

Omitting the new() constraint when creating a new instance.

The generic type parameter T is constrained with new() to require a parameterless constructor.

3fill in blank

hard

Fix the error in the generic class declaration by completing the constraint so that T must inherit from BaseEntity.

C Sharp (C#)

public class Manager<[1]> where T : BaseEntity { }

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AU

BK

CV

DT

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different letter in the constraint than in the generic declaration.

Forgetting to specify the base class in the constraint.

The generic type parameter T must be the same in the declaration and the constraint. Here, where T : BaseEntity means T inherits from BaseEntity.

4fill in blank

hard

Fill both blanks to declare a generic method where T must be a struct and U must implement IDisposable.

C Sharp (C#)

public void Process<[1], U>() where [1] : struct where U : [2] { }

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AT

BU

CIDisposable

DBaseEntity

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up the type parameter names and constraints.

Using a class name instead of an interface for the IDisposable constraint.

The first blank is the generic type parameter T constrained as a struct (value type). The second blank is the interface IDisposable that U must implement.

5fill in blank

hard

Fill all three blanks to declare a generic class where T must be a class, U must inherit from BaseEntity, and V must have a parameterless constructor.

C Sharp (C#)

public class Container<[1], [2], V> where T : class where U : BaseEntity where V : [3] { }

Drag options to blanks, or click blank then click option'

AT

BU

Cnew()

DV

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong parameter names in the constraints.

Forgetting the new() constraint for V.

The generic parameters are T, U, and V. The constraints specify that T is a class, U inherits from BaseEntity, and V has a parameterless constructor (new()).