Hiring guide for C++ Engineers

C++ Developer Hiring Guide

C++ is a high-level, general-purpose programming language, created by Bjarne Stroustrup at Bell Labs in 1979. It was developed as an extension of the C language, with additional features such as classes and objects, supporting the concept of object-oriented programming. C++ has been widely adopted in software engineering and is used for a variety of tasks, including system/software development and game programming. Its efficiency and flexibility have made it one of the most popular languages in the world. The language has been standardized by the International Organization for Standardization (ISO), with its latest version being C++20.

Ask the right questions secure the right C++ talent among an increasingly shrinking pool of talent.

First 20 minutes

General C++ app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in C++ application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

How would you declare a pointer in C++?
You would use the asterisk (*) symbol to declare a pointer in C++. For example, 'int* p;' declares a pointer to an integer.
What are the different types of inheritance in C++?
C++ supports several types of inheritance: single, multiple, multilevel, hierarchical, and hybrid inheritance.
Describe the difference between a class and a structure in C++.
In C++, the primary difference between a class and a structure is the default access level. For a class, members are private by default, while for a structure, they are public.
How would you use a function pointer in C++?
A function pointer can be declared and used like this: 'int (*funcPtr)(int,int);' This declares a pointer to a function that takes two integers as argument and returns an integer. You can assign a function to this pointer using 'funcPtr = &func;', where 'func' is a predefined function.
What is the purpose of the 'this' pointer in C++?
'This' is a keyword in C++ which is a pointer that points to the object which invokes the member function.
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What you’re looking for early on

Does the candidate demonstrate a strong understanding of C++ concepts?
Has the candidate shown problem-solving skills during the interview?
Is the candidate able to communicate effectively about technical topics?
Does the candidate have experience with the tools and technologies commonly used in your organization?

Next 20 minutes

Specific C++ development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

Describe the difference between overloading and overriding in C++.
Overloading refers to having multiple functions with the same name but different parameters, while overriding refers to a subclass providing a different implementation for a function that already exists in its superclass.
What are templates in C++?
Templates are a feature of the C++ programming language that allows functions and classes to operate with generic types. This allows a function or class to work on many different data types without being rewritten for each one.
How would you handle exceptions in C++?
C++ provides a mechanism to detect and handle runtime anomalies or exceptions. You can use the 'try', 'catch', and 'throw' keywords to work with exceptions. You wrap the code that could potentially throw an exception inside a 'try' block, and handle the exception in a 'catch' block.
What is a virtual function in C++?
A virtual function is a member function that you expect to be redefined in derived classes. When you refer to a derived class object using a pointer or a reference to the base class, you can call a virtual function for that object and execute the derived class's version of the function.
Describe the difference between the 'delete' and 'free' functions in C++.
'Delete' is an operator in C++ which deallocates memory and calls the destructor for the object, while 'free' is a function in C that just deallocates memory without calling the destructor.
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The ideal back-end app developer

What you’re looking to see on the C++ engineer at this point.

At this point, a skilled C++ engineer should demonstrate strong problem-solving abilities, proficiency in C++ programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with C++.

What does the following code do?
int x = 10; 
int y = 20; 
int z = x + y;
This code declares three integer variables x, y, and z. It assigns 10 to x and 20 to y. Then it adds x and y and assigns the result to z. So, z will be 30.
What will be the output of the following code?
for(int i = 0; i < 5; ++i) 
    std::cout << i; 
This code will output the numbers 0 through 4. This is because it's a loop that starts at 0 and continues as long as i is less than 5, incrementing i by 1 at the end of each iteration.
What does the following code do?
int arr[5] = {1, 2, 3, 4, 5}; 
int sum = 0; 
for(int i = 0; i < 5; ++i) 
    sum += arr[i]; 
This code calculates the sum of all elements in the array. It initializes an array of 5 integers, then it iterates over the array adding each element to the sum variable. At the end, sum will be the total of all elements in the array.
What does the following code do?
void foo() 
    // do something 
int main() 
    std::thread t(foo); 
This code creates a new thread that executes the function 'foo'. The main thread waits for this new thread to finish execution before it continues. This is done using the 'join' function, which blocks the calling thread until the thread t finishes its execution.

Wrap-up questions

Final candidate for C++ Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle C++ application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

What is the purpose of namespaces in C++?
Namespaces are used to organize code into logical groups and to prevent name collisions that can occur especially when your code base includes multiple libraries.
How would you implement polymorphism in C++?
Polymorphism in C++ can be implemented through the use of virtual functions. A base class pointer can point to objects of any of its subclasses, and when a virtual function is called through this pointer, the corresponding function in the derived class gets executed.
What is a copy constructor in C++?
A copy constructor is a member function which initializes an object using another object of the same class.

C++ application related

Product Perfect's C++ development capabilities

Beyond hiring for your C++ engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in C++ projects, and can engage in multiple capacities.