Rust vs. C++: Differences and use cases explained

Why programmers use Rust

Rust's feature set emphasizes thread safety, memory layout control and concurrency. Its built-in security is a plus for modern software and systems.

Within systems languages, concurrency can be fragile and error-prone. Such weaknesses can result in information loss and integrity deficits.

Threads enable different software components to execute simultaneously. Concurrency of threads can present challenges in software. Rust ensures safe concurrency of threads, which helps microservices applications operate as expected. The language is based on a principle of ownership in which any given value can be owned by a single variable at a time.

In Rust, compilation units are called crates. A crate is an atomic unit of code for the Rust compiler. Rust won't compile programs that attempt unsafe memory usage. Through syntax and language metaphors, the Rust compiler prevents thread- and memory-related problems such as null or dangling pointers and data races from occurring in production.

The static analysis tool in Rust's compiler, borrow checker, halts compilation before unsafe code can cause a memory error. Programmers must resolve these issues early in the development process. Borrow checker analyzes how value ownership can change across a program's lifetime. Values held by one place can be borrowed by other places in a code base. The borrow checker uses this set of rules to prevent data races in concurrent code.

The compiler also manages ownership distribution and memory allocation among objects to avoid issues at runtime. Memory safety prevents buffer overflows and protects against a class of bugs related to memory access and use. This means, for example, that increasing the amount of Rust code within a browser-based application will decrease the attack surface for breaches and vulnerabilities.

Rust offers powerful abstractions as well. Its rustup installer sets up the development environment and cross-compiling. All the elements necessary to produce Rust binaries exist in the same package.

How to get started with Rust

Developers new to Rust can pick up the core principles of the language by learning to use the Cargo package manager, which has numerous API bindings to common libraries and frameworks. Actix Web and Rocket are popular web frameworks for Rust.

Because the Cargo library doesn't rank the effectiveness of crates, developers need to experiment or poll the Rust community for input. The Rust community is inclusive and supportive. The Rust Foundation supports meaningful contributions to the ecosystem, furthers Rust outreach and promotes language adoption. It took over the language from Mozilla where it began as a side project in Mozilla Research.

Why programmers use C++

C++ originated as an extension of the C language for cross-platform programming. It offers effective functionalities, safety and ease of use. It has a three-year release cycle, with new features introduced regularly. Version C++23 was released in 2023, with C++26 development currently underway.

C++ has more complex syntax than some other languages and a great deal of abstraction, but it offers benefits for modern development. High levels of abstraction enable developers to encapsulate hardware and OS implementation details. It's a fit for embedded systems that require code to be close to the hardware, such as IoT devices, smartwatches and medical devices.

Abstract classes express pure virtual functions. Programmers can concentrate on grouping classes to make a program's codebase organized and understandable. Abstraction also reduces program duplication and promotes reusability. Developers can also improve program privacy with abstraction in the design, ensuring that users only see pertinent data.

C++ is a compiled language with written code translated directly into machine code. This construct makes the language fast, efficient and flexible. C++ takes advantage of hardware capabilities to accelerate scalability through low-level control. This feature suits video games, GUIs, scientific simulations and financial applications. It can handle large volumes of data, so it is effective for processing the enormous data sets necessary to produce immersive 3D AR/VR experiences.

C++ memory management allocates memory at runtime and deallocates it when it's not required. Free memory access in C++ can lead to buffer overruns and stack overflow vulnerabilities. These safety and security deficits require time and resources for debugging, a downside of C++. These concerns particularly affect domains that use embedded languages, such as automotive and medical fields and aerospace and aviation. Security guidelines for C++ yield memory safety with the language.

Code in the STL is tested and scrutinized by community members. The community's work enables programmers to simplify their code; write cleaner, faster code; and avoid maintenance issues. The library also includes generic algorithms and specifies the syntax and semantics for these instructions. Performance requirements for these algorithms correspond to accepted standards and benchmarks.

How to get started with C++

C++ coding requires a text editor and a compiler. Many beginners opt for IDEs like Visual Studio or Code::Blocks, which bundle tools and other features for users. For a more customizable setup, pair a text editor like Vim or Sublime Text with a standalone compiler such as GNU Compiler Collection or Clang.

As developers progress, they should familiarize themselves with the C++ STL and refer to the official website, which offers comprehensive documentation and tutorials. Additionally, the C++ community is active and supportive, with forums like Stack Overflow and the C++ subreddit offering help to newcomers. Developers can also join local user groups or attend conferences like CppCon to network and stay up to date with the latest developments in the ecosystem.

Key differences between Rust and C++

While both Rust and C++ are powerful low-level languages used for systems programming, they differ significantly in terms of their design, features and use cases.

Memory management

Rust employs a unique ownership system with borrowing rules, enforced at compile-time -- a model that ensures memory safety without a garbage collector, preventing issues like dangling pointers and data races and eliminating undefined behaviors.

C++ takes a different path, offering developers direct control over memory allocation and deallocation. It's worth mentioning that while modern C++ has introduced smart pointers and RAII (Resource Acquisition Is Initialization) to mitigate memory issues, it still permits undefined behaviors that can lead to security vulnerabilities.

Standard library philosophy

The standard library used by Rust is minimalistic by design and focuses on core functionality. Any additional features are available through external crates provided by the Cargo package manager.

C++'s STL is more comprehensive and offers a wide range of containers, algorithms and prebuilt utilities. This can lead to larger binaries but provides more built-in functionality, which is particularly useful for complex applications like operating systems.

Metaprogramming approaches

C++ uses template metaprogramming, enabling powerful compile-time computations. However, this can lead to complex syntax and longer compilation times.

Rust uses trait-based generics and macros for metaprogramming. While less powerful than C++ templates in some aspects, Rust offers a more unified and often more readable approach to generic programming.

Error handling

Rust uses the Result type for error handling, encouraging explicit error checking and propagation.

Conversely, C++ traditionally uses exceptions, which can result in performance overhead and potential resource leaks if not properly handled. Modern C++ also introduces std::optional and std::expected, allowing for a more explicit approach.

Compilation model

The compilation model for Rust is modular and uses crates as the basic unit, which allows for faster incremental builds and better dependency management.

C++'s traditional compilation relies on the preprocessor and separate compilation of translation units. This approach, while flexible, can lead to longer build times, especially in large projects with complex hierarchies. Modules introduced in C++20 aim to address some of these issues but are still in the process of widespread adoption.

What is the future of Rust and C++?

The future of Rust and C++ is a dynamic picture of coexistence and gradual transition. While C++ remains a powerhouse in systems programming, game development and operating systems, Rust is gaining significant traction due to its focus on memory safety and concurrency.

A recent White House report has encouraged developers to prioritize safer programming languages like Rust over C++ and C, particularly for critical infrastructure and security-sensitive applications. However, C++ isn't fading away. Its vast ecosystem, extensive codebase in critical systems and ongoing development ensure its relevance for years to come.

Likely, both low-level languages will continue to coexist. Rust could gradually take over in areas where memory safety is paramount, while C++ maintains its stronghold in performance-critical and legacy systems.

Editor's note: Kerry Doyle originally wrote this article in 2023, and Twain Taylor expanded it in 2024 to improve the reader experience.

Kerry Doyle writes about technology for a variety of publications and platforms. His current focus is on issues relevant to IT and enterprise leaders across a range of topics, from nanotech and cloud to distributed services and AI.

Twain Taylor is a technical writer, musician and runner. Having started his career at Google in its early days, today, Twain is an accomplished tech influencer. He works closely with startups and journals in the cloud-native space.