Chuck McCullough

Curly braces and object-oriented programming languages are pretty common. Among the top three for most developers are C++, C#, and Java.

C++ is the foundation from which the others derive. Therefore, this article focuses on the similarities and differences between C# vs. C++.

C++ overview

C++ was invented in 1979 by Bjarne Stroustrup. It is based on the original C language and was initially called “C with Classes.” The name was changed to C++ to indicate an increment beyond the original. This is opposed to D, a programming language released in 2001.

C++ has undergone many changes since its inception. A formal ANSI standard was published in 1999 with a significant revision in 2011. Minor revisions were also made in 2014 and 2017. Bottom line: C++ is very much alive.

Person in front of desktop and laptop coding

C++ is described as a high-performance, multi-paradigm language. It supports object-oriented language and procedural, generic, and functional programming styles. In any given web application or operating system, you could find all three styles in use.

Probably the most important feature of C++ is that it compiles into native machine code. Most programming today is done through interpretive languages such as JavaScript, Java, and C#. It provides a much faster execution potential when it’s run directly on the CPU without any supervision or translation. In the end, the developer controls everything about resource management in a C++ program.

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C# overview

Some people refer to Java as the kinder, gentler C++, but I disagree. Java is an extended subset of the language with a very different programming philosophy. On the other hand, I see C# as a closer fit to the description. Java architects who have referred to C# as a cheap knock-off of their platform are wrong!

The design of C# is much more aligned with C++. Through the incremental naming process, C# plays on the musical sharp note. In other words, it’s a halftone higher. Furthermore, there are a number of C++ features intentionally omitted from Java that are fully supported in C#.

C# was originally developed by Microsoft toward the end of the 20th century. It was standardized by the European Computer Manufacturer’s Association (ECMA) and ISO but was originally established as a closed source language connected to Microsoft’s .Net framework and Visual Studio. Today, C# is open source and platform-neutral. Version 10.0 was released in 2021 along with .Net 6.

C# vs. C++ similarities

Since C# was designed to be similar in both syntax and style to C++, both languages are statically linked. Unlike other scripting languages, the variables, parameters, and return types must be compatible through compile and run times. In addition, both C languages support references, pointers, and values. However, it’s rare in both C# and C++ to explicitly code pointer syntax.

Both languages treat method exception declarations the same and generate new first-class types from templates. For C#, this is based on generics.

Another similarity is the support of the struct and class keywords. In C++, most developers use the struct to define simple data objects while a class defines initial values for values and states of behavior. In C#, the struct has functional limitations and is treated as a value type. Thus, it formalizes traditional C++ usage.

Both languages also support compiler-deduced variable types. C++ uses the keyword auto, while C# uses var.

A critical similarity with C# vs. C++ is in their support for functional programming. C++ inherited its function pointers from C. Meanwhile, C# always had delegates, which are the equivalent of function pointers.

Both languages support functions as data and lay the groundwork for more sophisticated functional programming. Current versions of C++ and C# both support lambda expressions as an inline syntax for defining anonymous functions.

Inheritance, polymorphism, and interfaces are supported in both. Although, the mechanisms under the hood are different.

C# vs. C++ differences

Three significant differences jump out immediately between the two languages.

Memory management

C# uses a garbage collector to release dynamically allocated memory automatically. In C++, the developer must explicitly delete any memory allocations.

Through a technique known as Resource Allocation Is Initialization (RAII) and smart pointer templates, much of the tedium of resource management is automated. This gives the C++ program the advantage of immediate and efficient memory management without the need to explicitly free memory in the source code.

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Inheritance

Another significant difference is with inheritance. C++ supports multiple inheritances, while C# focuses on a single inheritance with a common Object base class. While this difference is significant in theory, in practice, C++ developers avoid multiple inheritances.

Since C++ doesn’t have a dedicated interface-type specifier, they prevent this situation by using syntax to implement interfaces. Nevertheless, I have not found either C# or C++ to be limiting in any way regarding inheritance, interfaces, or polymorphism.

Compiler target

The biggest difference concerns the compiler target. As mentioned earlier, C++ compiles to machine code and runs natively on the targeted CPU. Conversely, C# compiles to an intermediate language processed at runtime by the Common Language Runtime (CLR).

The CLR “machine” is virtual and must translate to the local hardware. Additionally, it also checks for uninitialized variables, null references, type mismatches, and array boundary violations. The CLR catches and stops a majority of common programming errors. On the other hand, a C++ application with similar errors plows through a system’s memory until the blue screen of death (BSoD) appears.

Compiling to an intermediate and running in a supervised or managed environment not only reduces common runtime errors but also provides security and significant dynamic capabilities not available in native applications. Through this method, C# programs discover other modules and even dynamically generate code on the fly.

C# vs. C++ performance

C++ Code:

long double CalcPi()
{
    long double result = 0;
    long double four = 4;
    for (long double denom = 1; denom < 1'000'000; denom += 4)
    {
        result += (four / denom) - (four / (denom + 2.0));
    }
    return result;
}

C# Code:

static double CalcPiDouble()
{
    double result = 0;
    double four = 4;
    for (double denom = 1; denom < 1_000_000; denom += 4)
    {
        result += (four / denom) - (four / (denom + 2.0));
    }
    return result;
}

C# and the .Net CLR produce high-speed programs.

I created a simple CPU-intensive program to calculate pi using the Gregory-Leibniz series of one million iterations. Using double precision floats, both the C# and C++ applications finished in less than one millisecond. The Java application took about three times as long.

Don’t make too much of this comparison, though. I can come up with benchmarks all day that favor one language over another.

The bottom line is, for most things, C# is fast enough while properly coded C++ totally screams when it comes to compilation and execution.

Final thoughts

I have coded many applications in C++, C#, and Java. Yet, I’m not religious about the language I use. In the end, you need to choose based on the type of application you’re building.

C++ is much more appropriate for CPU-intensive applications like video games and simulations. C# and Java are better at typical business applications, especially web applications.

Success with any development platform has more to do with architecture, design, patterns, and process. Each one has its pluses and minuses. Overall, select your language for the type of application and target platform. As a programmer, strive to be above the language specifics and focus on building a great system.

Take a look at What is C# as well as my video below to learn more about this topic. Also, check out my courses on C# and C++ to start your learning journey on Udemy.

Page Last Updated: December 2021