C++

Hire the Top 3% of Freelance C++ Developers

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Hire Freelance C++ Developers and Engineers

Abhimanyu Veer Aditya

Freelance C++ Developer

United StatesToptal Member Since March 7, 2019

Abhimanyu is a machine learning expert and entrepreneur with over 14 years of experience delivering analytics and predictive solutions for business and scientific applications. Working with small startups and Fortune 500 companies alike, his responsibilities included data science, engineering, operations, product and account management. He has a master’s degree in high performance computing and machine learning from Georgia Tech.

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George Cristea

Freelance C++ Developer

United StatesToptal Member Since July 1, 2017

George is a performance-oriented engineering leader with a substantial technology background and business proficiency. He specializes in designing and implementing large-scale distributed systems with a focus on performance and reliability. Throughout his career, George has consistently identified and managed the technology and operational risks with a strong sense of end-to-end ownership for complex software products.

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Kelly Ann Martines

Freelance C++ Developer

United StatesToptal Member Since May 18, 2018

Kelly has 12 years of experience working as a software engineer, focusing primarily on C++, C, and Java. She's worked on desktop applications in addition to concurrent systems, including multithreaded systems, clusters, or networks of embedded systems in avionics.

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Bryan Zimmerman

Freelance C++ Developer

United StatesToptal Member Since October 14, 2017

Bryan provides expert modern C/C++ development of object-oriented, highly concurrent, low latency, cross-platform software in the areas of big data, physics/engineering simulation/modeling, data communications, machine learning, networking, server-side, and embedded systems. He has vast experience with real-time, critical, 24/7, commercial, and defense systems.

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Konstantin Kanishchev

Freelance C++ Developer

FranceToptal Member Since August 31, 2013

Konstantin is a Theoretical Physicist with a strong background in C++, Python, and JavaScript programming. With deep experience in research-level software development, heavy data analysis (WLCG), and data visualization (d3.js), he provides high-level expertise in Physics, CS, and Applied Mathematics.

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Darien Pardinas Diaz

Freelance C++ Developer

United StatesToptal Member Since November 19, 2017

Darien is an accomplished software engineer with expertise in image processing, desktop application, and systems development. He worked as a research engineer in the early stages of his career, writing tools to acquire and process large volumes of scientific data. Later, he started working in the development of FDA compliant software for medical devices. Recently, he's been writing application software for a 3D printing company.

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Viktor Kirilov

Freelance C++ Developer

BulgariaToptal Member Since January 15, 2018

Viktor has more than four years of experience developing for the games and VFX industries, but since 2015, he's been mainly working on open source projects and contract work. He's passionate about game engines, high-performance code, data-oriented design, cryptocurrencies, minimizing friction, and incorporating good practices in the software development process such as testing and the use of tools.

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Ricardo Costa

Freelance C++ Developer

BrazilToptal Member Since July 3, 2018

Ricardo has over ten years of experience as a professional developer focusing on game development, computer graphics (rendering, computer vision, and VR/AR), artificial intelligence, and client/server systems. He has also developed a variety of desktop and server applications in C#, C++, and Python. He is passionate about researching cutting-edge technology, creating real-time, high-performance software, and optimizing complex systems.

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Dan Napierski

Freelance C++ Developer

United StatesToptal Member Since December 20, 2015

Dan is a software architect and technology professional focusing on applications of blockchain technologies. He has years of experience providing professional consulting services to clients ranging from startups to global corporations. He specializes in bringing rigorous testing and bulletproof code to tough engineering challenges. He has deep expertise in many aspects of artificial intelligence, blockchain, machine learning, and automation.

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Mike Hutton

Freelance C++ Developer

United StatesToptal Member Since June 5, 2014

Mike is a software architect and developer with over 25 years of experience developing large-scale mission-critical systems. He currently specializes in Java/J2EE development, C++/C development, and embedded systems for the IoT. He is an internationally recognized expert in the area of lottery gaming systems. He has been delivering solutions employing geographically diverse teams for the past 16 years.

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A Hiring Guide

Guide to Hiring a Great C++ Developer

C++ is a powerful general purpose multi-paradigm programming language. The language's immense set of features, its overall complexity, lack of elegant external tooling that other popular languages have, and access to low-level resources makes this one of the most difficult programming languages to master. Taming this mammoth beast requires much experience and wisdom.

Read Hiring Guide

C++ Hiring Resources

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Testimonials

Tripcents wouldn't exist without Toptal. Toptal Projects enabled us to rapidly develop our foundation with a product manager, lead developer, and senior designer. In just over 60 days we went from concept to Alpha. The speed, knowledge, expertise, and flexibility is second to none. The Toptal team were as part of tripcents as any in-house team member of tripcents. They contributed and took ownership of the development just like everyone else. We will continue to use Toptal. As a start up, they are our secret weapon.

Brantley Pace, CEO & Co-Founder

Tripcents

In addition to sharp technical skills, Faruk had a great attitude and is a really exceptional communicator. He always let us know where he was with his work, thoroughly and reliably. That's not always the case, and it made working remotely considerably easier. He was an easy integration into the team.

Leif Abraham, Co-Founder

AND CO Ventures Inc

I am more than pleased with our experience with Toptal. The professional I got to work with was on the phone with me within a couple of hours. I knew after discussing my project with him that he was the candidate I wanted. I hired him immediately and he wasted no time in getting to my project, even going the extra mile by adding some great design elements that enhanced our overall look.

Paul Fenley, Director

K Dunn & Associates

The developers I was paired with were incredible -- smart, driven, and responsive. It used to be hard to find quality engineers and consultants. Now it isn't.

Ryan Rockefeller, CEO

Radeeus

Toptal understood our project needs immediately. We were matched with an exceptional freelancer from Argentina who, from Day 1, immersed himself in our industry, blended seamlessly with our team, understood our vision, and produced top-notch results. Toptal makes connecting with superior developers and programmers very easy.

Jason Kulik, Co-Founder

ProHatch

As a small company with limited resources we can't afford to make expensive mistakes. Toptal provided us with an experienced programmer who was able to hit the ground running and begin contributing immediately. It has been a great experience and one we'd repeat again in a heartbeat.

Stuart Pocknee , Principal

Site Specific Software Solutions

We used Toptal to hire a developer with extensive Amazon Web Services experience. We interviewed four candidates, one of which turned out to be a great fit for our requirements. The process was quick and effective.

Abner Guzmán Rivera, CTO and Chief Scientist

Photo Kharma

Sergio was an awesome developer to work with. Top notch, responsive, and got the work done efficiently.

Dennis Baldwin, Chief Technologist and Co-Founder

PriceBlink

Working with Marcin is a joy. He is competent, professional, flexible, and extremely quick to understand what is required and how to implement it.

André Fischer, CTO

POSTIFY

We needed a expert engineer who could start on our project immediately. Simanas exceeded our expectations with his work. Not having to interview and chase down an expert developer was an excellent time-saver and made everyone feel more comfortable with our choice to switch platforms to utilize a more robust language. Toptal made the process easy and convenient. Toptal is now the first place we look for expert-level help.

Derek Minor, Senior VP of Web Development

Networld Media Group

Toptal's developers and architects have been both very professional and easy to work with. The solution they produced was fairly priced and top quality, reducing our time to launch. Thanks again, Toptal.

Jeremy Wessels, CEO

Kognosi

We had a great experience with Toptal. They paired us with the perfect developer for our application and made the process very easy. It was also easy to extend beyond the initial time frame, and we were able to keep the same contractor throughout our project. We definitely recommend Toptal for finding high quality talent quickly and seamlessly.

Ryan Morrissey, CTO

Applied Business Technologies, LLC

I'm incredibly impressed with Toptal. Our developer communicates with me every day, and is a very powerful coder. He's a true professional and his work is just excellent. 5 stars for Toptal.

Pietro Casoar, CEO

Ronin Play Pty Ltd

Working with Toptal has been a great experience. Prior to using them, I had spent quite some time interviewing other freelancers and wasn't finding what I needed. After engaging with Toptal, they matched me up with the perfect developer in a matter of days. The developer I'm working with not only delivers quality code, but he also makes suggestions on things that I hadn't thought of. It's clear to me that Amaury knows what he is doing. Highly recommended!

George Cheng, CEO

Bulavard, Inc.

As a Toptal qualified front-end developer, I also run my own consulting practice. When clients come to me for help filling key roles on their team, Toptal is the only place I feel comfortable recommending. Toptal's entire candidate pool is the best of the best. Toptal is the best value for money I've found in nearly half a decade of professional online work.

Ethan Brooks, CTO

Langlotz Patent & Trademark Works, Inc.

In Higgle's early days, we needed the best-in-class developers, at affordable rates, in a timely fashion. Toptal delivered!

Lara Aldag, CEO

Higgle

Toptal makes finding a candidate extremely easy and gives you peace-of-mind that they have the skills to deliver. I would definitely recommend their services to anyone looking for highly-skilled developers.

Michael Gluckman, Data Manager

Mxit

Toptal’s ability to rapidly match our project with the best developers was just superb. The developers have become part of our team, and I’m amazed at the level of professional commitment each of them has demonstrated. For those looking to work remotely with the best engineers, look no further than Toptal.

Laurent Alis, Founder

Livepress

Toptal makes finding qualified engineers a breeze. We needed an experienced ASP.NET MVC architect to guide the development of our start-up app, and Toptal had three great candidates for us in less than a week. After making our selection, the engineer was online immediately and hit the ground running. It was so much faster and easier than having to discover and vet candidates ourselves.

Jeff Kelly, Co-Founder

Concerted Solutions

We needed some short-term work in Scala, and Toptal found us a great developer within 24 hours. This simply would not have been possible via any other platform.

Franco Arda, Co-Founder

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How to Hire C++ Developers through Toptal

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Talk to One of Our Industry Experts

A Toptal director of engineering will work you to understand your goals, technical needs, and team dynamics.
2

Work With Hand-Selected Talent

Within days, we'll introduce you to the right C++ developer for your project. Average time to match is under 24 hours.
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Work with your new C++ developer for a trial period (pay only if satisfied), ensuring they're the right fit before starting the engagement.

FAQs

  • How are Toptal C++ developers different?

    At Toptal, we thoroughly screen our C++ developers to ensure we only match you with talent of the highest caliber. Of the more than 100,000 people who apply to join the Toptal network each year, fewer than 3% make the cut. You'll work with engineering experts (never generalized recruiters or HR reps) to understand your goals, technical needs, and team dynamics. The end result: expert vetted talent from our network, custom matched to fit your business needs. Start now.

  • Can I hire C++ developers in less than 48 hours through Toptal?

    Depending on availability and how fast you can progress, you could start working with a C++ developer within 48 hours of signing up. Start now.

  • What is the no-risk trial period for Toptal C++ developers?

    We make sure that each engagement between you and your C++ developer begins with a trial period of up to two weeks. This means that you have time to confirm the engagement will be successful. If you're completely satisfied with the results, we'll bill you for the time and continue the engagement for as long as you'd like. If you're not completely satisfied, you won't be billed. From there, we can either part ways, or we can provide you with another expert who may be a better fit and with whom we will begin a second, no-risk trial. Start now.

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C++

How to Hire a Great C++ Developer

C++ is a powerful general purpose multi-paradigm programming language. It powers some of the most performance intensive applications, and serves well to satisfy some particular niches, including but not limited to desktop applications, mobile applications, embedded applications, device drivers, game engine back ends, and more. You can use it in a variety of operating system environments like Android, Microsoft, or Unix. The language’s immense set of features, its overall complexity, lack of elegant external tooling that other popular languages have, and access to low-level resources makes this one of the most difficult programming languages to master. Taming this mammoth beast requires much experience and wisdom.

Harnessing the power of C++ requires nothing short of experience and wisdom

Harnessing the power of C++ requires nothing short of experience and wisdom

This hiring guide will help you identify C++ programmers who not only know the basics, but also understand its relevant concepts in-depth and know their way around the various challenges and pitfalls of this powerful programming language.

Basics

Questions like the following are meant to figure out how familiar the candidate is with C++, and to see if they know all the quirks and nuances of the language.

Q: Consider the following snippet of code:

string ext = "";
switch(ext) {
case "cpp":
case "cc":
        cout << "C++ source file" << endl;
case "java":
        cout << "Java source file" << endl;
default;
        cout << "Unknown extension" << endl;
}

Explain what, if anything, is wrong with it? How can you improve this code or work around any issue in it?

The switch statement, in C++, only accepts types that are integral, enumerated or class which has a single conversion function to an integral or enumerated type. std::string in C++ is not a primitive type.

In C/C++, switch statements are typically implemented as branch tables. Generating them for integers, integer-like or enumerated types is easy, which is not the case for strings.

One way to work around this limitation, in this particular case, is by using a map:

map<string, string> m;
m["cpp"] = "C++ source file";
m["cc"] = m["cpp"];
m["java"] = "Java source file";

string ext = "cc";
string r = m[ext];
if(r != "") {
	cout << r << endl;
} else {
	cout << "Unknown extension" << endl;
}

In case ext is expected to hold unknown values, you might want to use m.find(ext) != m.end() to determine if the key actually exists first. This is because the [] operator will automatically increase the container’s size everytime a non-existence key is used.

Q: How do you implement a variadic function in C++?

Functions that can accept a variable number of arguments can be declared using an ellipsis as its last parameter:

int int_sum(int n, ...)

For example, the following function will accept an argument, n, followed by any number of additional arguments.

int int_sum(int n, ...) {
	va_list args;
	va_start(args, n);
	int r = 0;
	while(n--) {
		int x = va_arg(args, int);
		r += x;
	}
	va_end(args);
	return r;
}

However, starting C++11, Variadic templates can be used to achieve similar results, as they are type safe and do not perform automatic type conversions.

Q: What are the different ways of passing parameters in a function call? Explain how they are different.

  • Pass by value: this causes the parameter’s value to be copied. Typically used for primitive types where the overhead of copying the value is minimal. In newer standards, such as C++11, with move semantics even complex objects may be efficiently passed by value.

  • Pass by reference: this causes the parameter inside the function to alias the variable passed when the function is called. Parameters can also be passed by const reference. This is very similar to what pass by value does, except the underlying object is not copied.

Additionally, pass by pointer can be considered another way of passing parameters. Although not the most recommended way of passing parameters, this works by passing the memory location of a variable by value, allowing the function to access the original variable’s contents, as if by reference. Typically used when it is important to pass NULL as the parameter. However, recommended ways of dealing with optional parameters involve the use of external libraries.

Q: What is the expected output for the following snippet of code:

int a[2];
int *x = &a[0];
*x = 2;
*(++x) = 4;
cout << a[0] << endl;
cout << a[1] << endl;

Explain.

The expected output of this program is:

2
4

This is because:

  • We start by declaring an array of 2 ints.
  • We are then taking a pointer to the first element in x.
  • Next, we are updating the value pointed at by x to 2.
  • Finally, we are Incrementing the pointer to move to the 2nd element and updating the value pointed at by x now to 4.

Q: How are exceptions handled in C++?

In C++, exceptions are handled using try-catch blocks:

try {
	// Something that may throw an exception
} catch(int ex) {
}

Exceptions are thrown using a throw statement:

throw 42;

Here, 42 is the parameter which will be passed to the handler as the only argument. Within a catch block, this parameter can be omitted to rethrow the current exception.

In a try-catch block, multiple exception handlers can be specified using multiple catch blocks. The type specified for the catch block will determine if it will be used to handle a particular exception.

And, Beyond

Even though C++ is closer to the metal than most other popular programming languages like PHP, there is still a lot going on under the hood. A great C++ software developer is very likely to have gained this knowledge, sometimes out of sheer curiosity and sometimes the hard way.

Q: In the following snippet of code:

int *arr1 = new int[10];
int arr2[10];
// ...
delete[] arr1;

Why is the delete[] statement necessary for variable arr1, but not for arr2? How can this be re-written using smart pointers?

Memory allocated dynamically using new or new[] must be deallocated to reclaim the used memory. This is because C++ doesn’t have a garbage collector to deallocate those resources automatically. The delete[] operator works on an array of objects that destroys each element before marking the memory as reusable on the heap.

The declaration line for arr1 could be replaced with the following:

unique_ptr<int[]> arr1(new int[10]);

This will automatically destroy and deallocate the array as soon as the smart pointer object goes out of scope.

Q: What is stack unwinding? What are its implications on object storage?

Stack unwinding happens when an exception is thrown. This is when function entries are removed from the stack up until an exception handler is found. In C++, stack unwinding will also cause stack variables to be destroyed automatically.

However, depending on how and when memory was allocated, stack winding may cause memory leaks. For example:

void leaky(bool panic) {
	SomeClass *scp = new SomeClass();
	if(panic) {
		throw 42;
	}
	delete scp;
}

Here, if panic is true, an exception will be thrown causing the program to never reach the delete statement and thus preventing the SomeClass instance to be deallocated from the heap.

Q: What is a function-try-block? What are these ideally used for?

A function-try-block allows you to attach a sequence of exception handlers after the function body that effectively treats the entire function body as a try block. This way, any exception that occurs with the function body may be handled by one of the catch blocks following it.

Ideally this syntax is used to log exceptions rather than handling them. Sometimes these are also used to modify the exception and rethrow them.

Q: What are templates? In terms of function declarations, how is this different from function overloading?

Templates are what allow C++ to define a group of classes, functions, types or variables in a parameterized manner. For example, the following definition of a function template:

template<typename T>
T add(T a, T b) {
	return a+b;
}

… will allow a developer to use the function add with any type that supports the + operator.

add(5, 1); // will use int add(int, int)
add(‘e’, ‘t’); // will use char add(char, char)

Templates allow classes, functions, etc. to be declared in a type “independent” way as long as the behavior remains the same. The compiler automatically generates the necessary code for every instance of the templated function or class used.

Templates are also not limited to types. They can also be used with expressions of a particular type. For example:

template<typename T, int a>
T add(T b) {
	return a+b;
}
add<int, 5>(1)

When it comes to functions, unlike function templates, function overloading requires you to explicitly define the behavior of each instance of the function.

Q: What are special member functions in C++? Briefly explain their use and state their defaults when not explicitly defined.

The default constructor, destructor, copy constructor and copy assignment (along with move constructor and assignment as introduced in C++11) are the special member functions in C++.

The default constructor is called when objects of a class are instantiated without passing any arguments. When no constructors are defined for a class, the default constructor is automatically defined as a function that is no-op.

The destructor, meant to serve as the opposite of constructors, allows an object to clean after itself before it is deallocated from memory. When not defined, similar to the default constructor, a no-op function is automatically declared on the class.

The copy constructor is essentially a constructor that accepts an argument of its own type by const reference. This constructor is meant to create a clone of the object being passed. When not defined, a default that copies all the members of the object is defined if and only if no move constructor or assignment function is defined.

The copy assignment function is called when an object is being assigned to another variable of the same type that is already initialized. Automatic default declaration follows the same rule as copy constructor as stated above.

Move constructor and assignment functions are similar to copy constructor and assignment functions, except that these are called when the values of the source object are no longer necessary and may be taken over by the destination object. The default behavior moves all members, but is automatically declared only when no copy constructor, assignment function, or move assignment function is declared.

Q: Does C++ allow multiple inheritance? What are some pitfalls of multiple inheritance and how can you work around them in C++?

C++ allows multiple inheritance. A class can extend one or more classes by providing a comma-separated list of their names:

class SomeClass: public ParentClass1, public ParentClass2 {
	// …
};

One of the pitfalls of multiple inheritance is ambiguity. For example, both ParentClass1 and ParentClass2 in the example above may have methods declared with the exact same signature. Attempting to call these inherited methods on SomeClass will cause the compiler to complain about this ambiguity - exactly which inherited method should be called? This issue can be worked around with explicit qualification:

SomeClass *sc = new SomeClass;
sc->ParentClass1::parentMethod();
sc->ParentClass2::parentMethod();

Another with multiple inheritance is the diamond problem. Let us assume that both ParentClass1 and ParentClass2 were derived from the same class:

class ParentClass1: public RootClass { /* … */ };
class ParentClass2: public RootClass { /* … */ };

… and if the RootClass had some public method named rootMethod, then calling that method would automatically result in ambiguity. This is because both ParentClass1 and ParentClass2 has inherited these methods, and to SomeClass this is ambiguous. One possible way of working around this issue is to use virtual inheritance:

class ParentClass1: public virtual RootClass { /* … */ };
class ParentClass2: public virtual RootClass { /* … */ };

Wrap up

The questions outlined in this guide cover some basic and some tricky aspects of C++ programming. But just like its possibilities, the language’s hidden surprises are limitless, and that makes it difficult to cover everything about C++ in interviews. Therefore it is essential to evaluate a candidate’s competency, skill set, and deep understanding of C++ through their ability to convey their ideas clearly and vividly.

We hope these questions will help you as a guide in your search for a true high-quality C++ expert in either a full-time or part-time role. These rare elites may be hard to come by, but they will clearly stand out from the rest of the pack for your development team.

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