Classes and Objects in C#
15 questions · 12 min · Medium
Constructors in C#
Test your knowledge of constructors in C#, including default constructors, parameterized constructors, static constructors, constructor overloading, inheritance, and object initialization.
- 15
- Questions
- 12 min
- Time limit
- Medium
- Difficulty
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All 15 questions and answers Spoilers: this shows the questions and answers. Try the quiz first! Open
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1. What is the primary purpose of a constructor in C#?
- A. To initialize an object when it is created
- B. To destroy an object
- C. To define a namespace
- D. To handle exceptions
Show answer
A. To initialize an object when it is created
A constructor is called when an object is created and is commonly used to initialize the object's state.
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2. Which characteristic distinguishes a constructor from a regular method in C#?
- A. A constructor has the same name as its class and has no return type
- B. A constructor must always return void
- C. A constructor must have a different name from its class
- D. A constructor must be declared static
Show answer
A. A constructor has the same name as its class and has no return type
A constructor uses the class name and does not declare a return type, including void.
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3. When is an instance constructor normally called?
- A. When an instance of the class is created
- B. When the class is compiled
- C. When the application is installed
- D. When the namespace is imported
Show answer
A. When an instance of the class is created
Instance constructors execute as part of creating an instance of the class.
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4. What happens if a class has no instance constructor declared and no constructor with parameters?
- A. The compiler can provide a parameterless instance constructor
- B. The class cannot be instantiated
- C. A static constructor is automatically created instead
- D. The class becomes abstract
Show answer
A. The compiler can provide a parameterless instance constructor
If no instance constructors are declared, the compiler can provide a public parameterless constructor for a class.
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5. Which of the following is a parameterized constructor?
- A. public Student() { }
- B. public Student(int id) { }
- C. public void Student() { }
- D. static Student() { }
Show answer
B. public Student(int id) { }
A parameterized constructor accepts one or more parameters that can be used to initialize an object.
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6. Can a C# class have multiple constructors with different parameter lists?
- A. Yes
- B. No
- C. Only if all are static
- D. Only in abstract classes
Show answer
A. Yes
C# supports constructor overloading, allowing multiple constructors with different parameter lists.
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7. What is constructor overloading?
- A. Defining multiple constructors with different parameter lists
- B. Calling the same constructor repeatedly
- C. Creating constructors in different namespaces
- D. Using a constructor as a method
Show answer
A. Defining multiple constructors with different parameter lists
Constructor overloading allows a class to provide multiple ways to initialize objects by defining constructors with different parameter lists.
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8. Which keyword is used to call another constructor in the same C# class?
- A. base
- B. this
- C. self
- D. parent
Show answer
B. this
A constructor initializer such as : this(...) calls another constructor in the same class.
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9. Which keyword is used in a constructor initializer to call a constructor of the base class?
- A. this
- B. base
- C. parent
- D. super
Show answer
B. base
The base keyword can be used in a constructor initializer to invoke a constructor of the base class.
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10. What is a static constructor used for in C#?
- A. Initializing static data or performing one-time initialization for a type
- B. Initializing every object instance separately
- C. Destroying static objects
- D. Overriding instance methods
Show answer
A. Initializing static data or performing one-time initialization for a type
A static constructor performs initialization for a type and is executed automatically at most once per application domain or relevant type initialization context.
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11. Which statement about a static constructor is correct?
- A. It cannot have parameters
- B. It must always be public
- C. It can be called directly like an instance constructor
- D. It must return void
Show answer
A. It cannot have parameters
A static constructor cannot have parameters and cannot have an access modifier.
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12. Can a constructor be inherited by a derived class?
- A. Yes, all constructors are inherited
- B. No, constructors are not inherited
- C. Only public constructors are inherited
- D. Only static constructors are inherited
Show answer
B. No, constructors are not inherited
Constructors are not inherited by derived classes. A derived class can explicitly invoke an accessible base constructor.
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13. What is the purpose of the `base(...)` constructor initializer in a derived class?
- A. To invoke a constructor of the base class
- B. To create a new namespace
- C. To prevent inheritance
- D. To call a static method
Show answer
A. To invoke a constructor of the base class
The base constructor initializer allows a derived class constructor to explicitly select and pass arguments to an accessible base class constructor.
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14. Which statement about constructors is correct?
- A. Constructors can have return types
- B. Constructors can be overloaded
- C. Constructors must always be private
- D. Constructors can be overridden
Show answer
B. Constructors can be overloaded
C# supports constructor overloading, but constructors do not have return types and cannot be overridden.
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15. What is the main difference between an instance constructor and a static constructor?
- A. An instance constructor initializes an object instance, while a static constructor initializes type-level static state
- B. A static constructor is inherited while an instance constructor is not
- C. An instance constructor must always have parameters
- D. A static constructor returns an object
Show answer
A. An instance constructor initializes an object instance, while a static constructor initializes type-level static state
Instance constructors are associated with individual objects, while static constructors perform one-time initialization associated with the type itself.