C++ Interview Questions and Answers (Part-G)

Certainly! Here are some more C++ interview questions along with their answers:

61. What are rvalue references and move semantics in C++?

• Rvalue references are references that bind to temporary objects or rvalues. Move semantics in C++ use rvalue references to enable efficient transfer of resources from one object to another without expensive deep copies. This is achieved using std::move to cast an lvalue to an rvalue reference.

62. What is a lambda capture list in C++? Explain when and why you would use different capture modes.

• A lambda capture list specifies which variables from the enclosing scope are captured by the lambda function. The capture list can use three capture modes:
  • Capture by Value ([var]): Captures a copy of the variable var.
  • Capture by Reference ([&var]): Captures the variable var by reference.
  • Capture by Value with Mutable ([var] mutable): Captures a copy of the variable var and allows modifications to it within the lambda.

63. How do you implement a custom comparator for sorting algorithms in C++?

• To implement a custom comparator for sorting, you can define a function or lambda that takes two elements as input and returns true if the first element should come before the second element in the sorted order. You can then pass this comparator function or lambda as the third argument to the sorting algorithm (e.g., std::sort, std::stable_sort).

64. What is the difference between the pre-increment operator (++i) and the post-increment operator (i++) in C++?

• The pre-increment operator (++i) increments the value of i and returns the updated value. It increments the value before any other operation.
• The post-increment operator (i++) returns the current value of i and then increments it. It increments the value after any other operation.

65. Explain the C++ constexpr keyword and its significance in compile-time evaluation.

• The constexpr keyword is used to declare variables, functions, and constructors that can be evaluated at compile time. constexpr objects must have their values determined at compile time, and constexpr functions can be called with constant expressions and produce constant expressions as results.

66. What are C++ user-defined literals, and how are they used?

• User-defined literals allow you to define custom suffixes for numeric literals, enabling you to create custom data types or conversions for literals. They use the format operator"" suffix to define the literal operator function.

67. How do you handle memory management and avoid memory leaks when working with raw arrays in C++?

• When working with raw arrays in C++, it is crucial to manage memory properly. Always use smart pointers like std::unique_ptr or std::shared_ptr to manage dynamic arrays to avoid memory leaks. If you are using raw pointers, make sure to deallocate the memory using delete[] after its use.

68. What is the std::tuple class in C++? How can you access elements from a tuple?

• std::tuple is a class template that represents a fixed-size collection of heterogeneous elements. Elements in a tuple can be of different types. To access elements, you can use std::get to retrieve an element by its index or std::tie to unpack the tuple elements into separate variables.

69. Explain the explicit keyword in C++ and its role in preventing implicit type conversions.

• The explicit keyword is used to specify that a constructor or conversion operator should not be used for implicit type conversions. It prevents accidental type conversions and ensures that the compiler only uses the constructor when it is explicitly requested.

70. What are C++ smart pointers, and how do they help with memory management?

• C++ smart pointers (std::unique_ptr, std::shared_ptr, std::weak_ptr) are RAII-based classes that automatically manage the memory allocated to an object. They ensure proper deallocation of memory when the object goes out of scope, preventing memory leaks and simplifying memory management.

Keep practicing these questions and reviewing C++ concepts to excel in your interviews. Understanding these concepts thoroughly will not only help you answer questions confidently but also improve your C++ programming skills. Good luck!