C++ Interview Questions – Expert Level
41. What is the main use of the keyword “Volatile”?
Just like its name, things can change suddenly and unexpectantly; So it is used to inform the compiler that the value may change anytime. Also, the volatile keyword prevents the compiler from performing optimization on the code. It was intended to be used when interfacing with memory-mapped hardware, signal handlers, and machine code instruction.
For more information, refer to this Volatile
42. Define storage class in C++ and name some
Storage class is used to define the features(lifetime and visibility) of a variable or function. These features usually help in tracing the existence of a variable during the runtime of a program.
Syntax:
storage_class var_data_type var_name;
Some types of storage classes:
Examples of storage class
For more information, refer to Storage Class
43. What is a mutable storage class specifier? How can they be used?
Just like its name, the mutable storage class specifier is used only on a class data member to make it modifiable even though the member is part of an object declared as const. Static or const, or reference members cannot use the mutable specifier. When we declare a function as const, this pointer passed to the function becomes const.
44. Define the Block scope variable.
So the scope of a variable is a region where a variable is accessible. There are two scope regions, A global and block or local.
A block scope variable is also known as a local scope variable. A variable that is defined inside a function (like main) or inside a block (like loops and if blocks) is a local variable. It can be used ONLY inside that particular function/block in which it is declared. a block-scoped variable will not be available outside the block even if the block is inside a function.
For more information, refer to Scope of a variable
45. What is the function of the keyword “Auto”?
The auto keyword may be used to declare a variable with a complex type in a straightforward fashion. You can use auto to declare a variable if the initialization phrase contains templates, pointers to functions, references to members, etc. With type inference capabilities, we can spend less time having to write out things the compiler already knows. As all the types are deduced in the compiler phase only, the time for compilation increases slightly but it does not affect the runtime of the program.
For more information, refer to Auto in C++
46. Define namespace in C++.
Namespaces enable us to organize named items that would otherwise have global scope into smaller scopes, allowing us to give them namespace scope. This permits program parts to be organized into distinct logical scopes with names. The namespace provides a place to define or declare identifiers such as variables, methods, and classes.
Or we could say that A namespace is a declarative zone that gives the identifiers (names of types, functions, variables, and so on) within it a scope. Namespaces are used to arrange code into logical categories and to avoid name clashes, which might happen when you have many libraries in your code base.
For more information, refer to Namespace in C++
47. When is void() return type used?
The void keyword, when used as a function return type, indicates that the function does not return a value. When used as a parameter list for a function, void indicates that the function takes no parameters. Non-Value Returning functions are also known as void functions. They’re called “void” since they’re not designed to return anything. True, but only partially. We can’t return values from void functions, but we can certainly return something. Although void functions have no return type, they can return values.
For more information, refer to Void return type.
48. What is the difference between shallow copy and deep copy?
Shallow Copy | Deep Copy |
|---|---|
| In Shallow copy, a copy of the original object is stored and only the reference address is finally copied. In simple terms, Shallow copy duplicates as little as possible | In Deep copy, the copy of the original object and the repetitive copies both are stored. In simple terms, Deep copy duplicates everything |
| A shallow copy of a collection is a copy of the collection structure, not the elements. With a shallow copy, two collections now share individual elements. | A deep copy of a collection is two collections with all of the elements in the original collection duplicated. |
| A shallow copy is faster | Deep copy is comparatively slower. |
For more information, refer to Shallow copy VS Deep Copy
49. Can we call a virtual function from a constructor?
Yes, we can call a virtual function from a constructor. But it can throw an exception of overriding.
50. What are void pointers?
Just like its name a void pointer is a pointer that is not associated with anything or with any data type. Nevertheless, a void pointer can hold the address value of any type and can be converted from one data type to another.
For more, information refers to Void Pointer in C++
C++ Interview Questions and Answers (2024)
C++ – the must-known and all-time favourite programming language of coders. It is still relevant as it was in the mid-80s. As a general-purpose and object-oriented programming language is extensively employed mostly every time during coding. As a result, some job roles demand individuals be fluent in C++. It is utilized by top IT companies such as Evernote, LinkedIn, Microsoft, Opera, NASA, and Meta because of its dependability, performance, and wide range of settings in which it may be used. So, to get into these companies, you need to be thorough in these top 50 C++ interview questions which can make you seem like an expert in front of recruiters.
To make you interview-ready, we have brought the Top 50 C++ interview questions for beginner, intermediate and experienced which you must definitely go through in order to get yourself placed at top MNCs.