C++ programming interview questions and answers

 Preparing for a C++ programming interview requires not only a strong understanding of the language but also familiarity with common programming concepts and problem-solving techniques. To help you excel in your C++ interview, we have compiled a list of frequently asked questions along with their answers. Let's dive in:

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What is C++?

C++ is a general-purpose programming language that extends the C programming language with additional features such as classes, templates, and object-oriented programming (OOP) capabilities. It provides high-level abstractions while maintaining low-level control, making it suitable for a wide range of applications.

Differentiate between C and C++.

C++ is an extension of C, so it retains most of the syntax and features of C. However, C++ introduces several additional features, including classes and objects, templates, exception handling, and namespaces, which enable OOP and provide higher-level abstractions compared to C.

What is the difference between "new" and "malloc" in C++?

"new" and "malloc" are used for dynamic memory allocation. "new" is an operator in C++ that performs memory allocation and calls the constructor for object initialization. In contrast, "malloc" is a library function in C that only allocates memory and does not initialize objects or call constructors. It is typically used for memory allocation in C-style code.

Explain the concept of function overloading.

Function overloading in C++ allows multiple functions with the same name but different parameters to coexist. The compiler differentiates between these functions based on the number, type, and order of the parameters. Function overloading enables code reusability and improves code readability by providing different versions of a function tailored to specific scenarios.

What are the access specifiers in C++?

C++ provides three access specifiers: "public," "private," and "protected." These specifiers control the visibility and accessibility of class members. "public" members are accessible from anywhere, "private" members are accessible only within the class itself, and "protected" members are accessible within the class and its derived classes.

What is the difference between pass by value and pass by reference?

In pass by value, the function receives a copy of the argument, and any modifications made within the function do not affect the original value. In pass by reference, the function receives a reference to the original variable, allowing modifications to be reflected outside the function. Pass by reference is often more efficient and useful when modifying large objects or when the function needs to return multiple values.

Explain the concept of virtual functions and polymorphism.

In C++, a virtual function is a member function of a class that can be overridden in derived classes. It enables dynamic binding, allowing the correct function implementation to be determined at runtime based on the object's actual type rather than its declared type. Polymorphism, achieved through virtual functions, allows objects of different classes to be treated uniformly by invoking the appropriate function based on the object's type.

What is a template in C++?

Templates in C++ allow the creation of generic classes or functions that can operate on different data types without code duplication. They enable code reusability and provide flexibility in designing algorithms and data structures that work with various data types. Template classes are instantiated with specific types at compile-time, generating specialized code for each type.

What are the differences between a shallow copy and a deep copy?

In C++, a shallow copy copies the memory address of an object, resulting in two objects pointing to the same memory location. Changes made to one object will be reflected in the other. A deep copy, on the other hand, creates a new object with its own memory space and copies the values of the original object. Modifications to one object will not affect the other.

How does exception handling work in C++?

Exception handling in C++ allows the detection and handling of exceptional conditions during program execution. It involves three keywords: "try," "catch," and "throw." The "try" block encloses code that may throw an exception. If an exception is thrown, it is caught by the corresponding "catch" block that handles the exception. The "throw" keyword is used to explicitly raise an exception.

What is the role of "const" keyword in C++?

The "const" keyword in C++ is used to declare variables, member functions, or function parameters as read-only or immutable. It ensures that the value of the variable cannot be modified once assigned. Const-correctness helps enforce data integrity, improves code maintainability, and enables compiler optimizations.

Explain the concept of function templates.

Function templates in C++ allow the creation of generic functions that can operate on different data types. Instead of writing multiple functions for each data type, a single function template can handle multiple types. The template keyword is used to define function templates, and type parameters are specified within angle brackets (<>) to represent different data types.

What are the differences between a class and a struct in C++?

In C++, the only difference between a class and a struct is the default access specifier. In a class, members are private by default, while in a struct, members are public by default. Structs are typically used for simple data structures without associated behavior, while classes are used for encapsulating data and behavior through OOP principles.

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How do you handle memory management in C++?

C++ offers several approaches to memory management. Manual memory management can be done using "new" and "delete" operators for dynamic memory allocation and deallocation. However, it requires careful management to avoid memory leaks or dangling pointers. Alternatively, smart pointers, such as "unique_ptr" and "shared_ptr," can be used to automate memory management and provide automatic deallocation when the object is no longer needed.

Describe the concept of operator overloading.

Operator overloading in C++ allows the customization of the behavior of operators for user-defined classes or types. It enables the use of operators, such as +, -, *, /, etc., with user-defined objects. By overloading operators, you can define how objects of your class interact with operators, making the code more intuitive and expressive.

These are just a few of the commonly asked C++ programming interview questions. It's important to thoroughly understand the concepts behind these questions and be able to apply them to real-world scenarios. Practicing coding exercises and reviewing additional interview questions will further enhance your preparation. Good luck with your C++ interview!