1. What is C#?
a. A high-level programming language
b. A low-level programming language
c. A markup language
Answer: a
2. What is the difference between C# and C++?
a. C# is object-oriented, while C++ is not
b. C# is a managed language, while C++ is unmanaged
c. C# is a scripting language, while C++ is a compiled language
Answer: b
3. Which of the following is not a primitive type in C#?
a. bool
b. char
c. decimal
d. byte array
Answer: d
4. What is a delegate?
a. An object that represents a method
b. A function that returns a value
c. A programming construct used to create nested classes
Answer: a
5. What is the purpose of using attributes in C#?
a. To add metadata to code elements
b. To define a new data type
c. To declare global variables
Answer: a
6. Which keyword is used to define a class in C#?
a. class
b. struct
c. interface
Answer: a
7. Which of the following is not a control structure in C#?
a. if
b. for
c. switch
d. throw
Answer: d
8. What is the purpose of the using directive in C#?
a. To include a namespace
b. To create a new object
c. To declare a new method
Answer: a
9. What is the difference between string and StringBuilder in C#?
a. String is immutable, while StringBuilder is mutable
b. String can be concatenated using the ‘+’ operator, while StringBuilder uses the Append method
c. String is a value type, while StringBuilder is a reference type
Answer: a
10. What is a namespace in C#?
a. A way to group related classes
b. An array of strings
c. An integer value that represents a memory address
Answer: a
11. What is the purpose of the base keyword in C#?
a. To call a constructor in the base class
b. To reference a derived class from the base class
c. To declare a new instance of an object
Answer: a
12. Which of the following is the correct syntax for a switch statement in C#?
a. switch (variable) { case value1: break; case value2: break; default: break; }
b. switch (case value1) { break; case value2: break; default: break; }
c. switch (variable) { value1: break; value2: break; }
Answer: a
13. What is the purpose of the ref keyword in C#?
a. To pass a parameter by reference
b. To create a new reference type
c. To call a method in a class
Answer: a
14. Which of the following is not a valid access modifier in C#?
a. public
b. internal
c. protected
d. friend
Answer: d
15. What is the difference between a struct and a class in C#?
a. Structs are value types, while classes are reference types
b. Structs are created on the stack, while classes are created on the heap
c. Structs can have default constructors, while classes cannot
Answer: a
16. What is the purpose of the lock keyword in C#?
a. To lock a method from being accessed by multiple threads simultaneously
b. To lock a class from being accessed by multiple threads simultaneously
c. To lock a variable from being accessed by multiple threads simultaneously
Answer: c
17. What is the difference between a public and private class in C#?
a. A public class can be accessed from any other part of the program, while a private class can only be accessed within the same namespace
b. A public class can be inherited by other classes, while a private class cannot be inherited
c. There is no such thing as a private class in C#
Answer: a
18. What is the purpose of the this keyword in C#?
a. To refer to the current instance of a class
b. To create a new instance of an object
c. To declare a new method in a class
Answer: a
19. What is a constructor in C#?
a. A method that is called automatically when an object is created
b. A method that is called when an object is destroyed
c. A method that is used to create a new class
Answer: a
20. What is the purpose of the sealed keyword in C#?
a. To prevent a class from being inherited
b. To prevent a method from being overridden in a derived class
c. To prevent a variable from being changed after it is initialized
Answer: a
21. What is an interface in C#?
a. A contract that defines a set of methods and properties
b. A type of data structure used to store multiple values
c. A keyword used to define a new class
Answer: a
22. What is the difference between an abstract class and an interface in C#?
a. An abstract class can have implementation code, while an interface cannot
b. An abstract class can be instantiated, while an interface cannot
c. An abstract class can inherit from other classes, while an interface cannot
Answer: a
23. What is the purpose of the IEnumerable interface in C#?
a. To provide a way to iterate over a collection of objects
b. To provide a way to compare two objects for equality
c. To provide a way to sort a collection of objects
Answer: a
24. What is the purpose of the yield keyword in C#?
a. To return a value from a method
b. To suspend the execution of a method and return control to the calling method
c. To create an iterator block that returns a sequence of values
Answer: c
25. What is the difference between an event and a delegate in C#?
a. An event is a delegate with an associated event handler method
b. An event is a keyword used to declare a new delegate
c. An event is a method that can be chained with other methods
Answer: a
26. What is the difference between an override and a virtual method in C#?
a. An override method provides a new implementation for a base class method, while a virtual method can be overridden in a derived class
b. An override method can only be called from within the same class, while a virtual method can be called from a derived class
c. There is no difference between an override and a virtual method in C#
Answer: a
27. What is the purpose of the async keyword in C#?
a. To create a new asynchronous method
b. To create a new synchronously executed method
c. To specify a timeout value for a method
Answer: a
28. What is a lambda expression in C#?
a. A shorthand way of writing anonymous methods
b. A way of creating a new instance of an object
c. A way of defining a new data type
Answer: a
29. What is the difference between a class and an object in C#?
a. A class is a blueprint for creating objects, while an object is an instance of a class
b. A class is a value type, while an object is a reference type
c. There is no difference between a class and an object in C#
Answer: a
30. What is the purpose of the default keyword in C#?
a. To return the default value for a data type
b. To create a new instance of an object
c. To declare a new method in a class
Answer: a
31. What is the purpose of the throw keyword in C#?
a. To raise an exception
b. To exit a loop
c. To return a value from a method
Answer: a
32. What is the difference between a dynamic and static data type in C#?
a. The type of data that can be stored
b. The ability to change the data type at runtime
c. The way the data is stored in memory
Answer: b
33. What is the purpose of the as keyword in C#?
a. To perform a cast operation with additional error handling
b. To create a new instance of a type
c. To define a new data type
Answer: a
34. What is the difference between a property and a field in C#?
a. A property encapsulates a field and provides access to it, while a field is a variable that stores the data
b. A property is a keyword used to declare a new data type, while a field is a keyword used to declare a new variable
c. There is no difference between a property and a field in C#
Answer: a
35. What is the difference between an explicit and implicit operator in C#?
a. An explicit operator requires a type cast, while an implicit operator does not
b. An explicit operator can only be defined for value types, while an implicit operator can be defined for any type
c. There is no difference between an explicit and implicit operator in C#
Answer: a
36. What is the purpose of the extern keyword in C#?
a. To declare a method that is implemented in an external DLL
b. To create a new instance of an object
c. To define a new data type
Answer: a
37. What is the difference between a static and instance method in C#?
a. A static method can be called on the class itself, while an instance method can only be called on an instance of the class
b. A static method is a keyword used to declare a new method, while an instance method is a keyword used to declare a new variable
c. There is no difference between a static and instance method in C#
Answer: a
38. What is the purpose of the checked keyword in C#?
a. To check for overflow when performing arithmetic operations
b. To check if a value is equal to null
c. To check if a value is within a specified range
Answer: a
39. What is the difference between a try and catch block in C#?
a. A try block contains code that may throw an exception, while a catch block handles the exception if one is thrown
b. A try block is used to iterate over a collection of objects, while a catch block is used to sort the objects
c. There is no difference between a try and catch block in C#
Answer: a
40. What is the purpose of the out keyword in C#?
a. To pass a value by reference
b. To create a new instance of an object
c. To declare a new method in a class
Answer: a
41. What is the purpose of the using statement in C#?
a. To dispose of an object when it is no longer needed
b. To create a new instance of an object
c. To define a new data type
Answer: a
42. What is the difference between a public and private method in C#?
a. A public method can be accessed from any other part of the program, while a private method can only be accessed within the same class
b. A public method can be overridden in a derived class, while a private method cannot
c. There is no difference between a public and private method in C#
Answer: a
43. What is the difference between a null and an empty string in C#?
a. A null string is one that has not been assigned a value, while an empty string is one that has been assigned a value of “”
b. A null string is one that contains no characters, while an empty string is one that contains whitespace characters
c. There is no difference between a null and empty string in C#
Answer: a
44. What is the purpose of the out-of-band data in C#?
a. To send additional data during a network connection
b. To serialize an object for transmission
c. To define a new data type
Answer: a
45. What is the purpose of the break and continue keywords in C#?
a. To exit a loop and skip to the next iteration, respectively
b. To define a new data type
c. To create a new object
Answer: a
46. What is the difference between a base and derived class in C#?
a. A base class is the class from which a derived class inherits, while a derived class is the class that inherits from the base class
b. A base class is a keyword used to declare a new class, while a derived class is a keyword used to declare a new data type
c. There is no difference between a base and derived class in C#
Answer: a
47. What is the purpose of the var keyword in C#?
a. To implicitly declare the type of a variable
b. To explicitly declare the type of a variable
c. To declare a new data type
Answer: a
48. What is the difference between a public and private field in C#?
a. A public field can be accessed from any other part of the program, while a private field can only be accessed within the same class
b. A public field can be overridden in a derived class, while a private field cannot
c. There is no difference between a public and private field in C#
Answer: a
49. What is the difference between a synchronous and asynchronous method in C#?
a. A synchronous method executes in a single thread, while an asynchronous method can execute in multiple threads
b. A synchronous method returns a value immediately, while an asynchronous method returns a value at a later time
c. There is no difference between a synchronous and asynchronous method in C#
Answer: a
50. What is the purpose of the protected keyword in C#?
a. To allow access to members from derived classes
b. To allow access to members from any other part of the program
c. To allow access to members only within the same class
Answer: a
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