Rust vs C++ Comparison

C++ has long been the industry standard for performance-critical applications, from operating systems and drivers to game engines and financial systems. However, Rust has emerged as a compelling alternative, offering memory safety, modern tooling, and concurrency without sacrificing control or performance.

In order to explain why Rust is a safer and faster language than C++, we decided to create a Rust vs C++ comparison that clearly shows the differences between these two languages. This article will be useful for people who are familiar with C++ but are new to Rust development and want to choose the language that best fits their project.

Why is Rust growing in popularity?

Rust is a general-purpose language originally developed by Mozilla and now maintained by the Rust Foundation. It started as an internal project to develop Firefox and evolved into a strong alternative to C++ in systems programming.

The most significant reason for Rust’s growing popularity is its approach to memory safety. C++ gives developers full control over memory, but that freedom comes with issues like null pointer dereferencing, buffer overflows, and use-after-free bugs. Rust eliminates these concerns through its ownership model and compile-time borrow checking. These features guarantee memory safety without relying on garbage collection.

While C++ vs Rust performance is a hot topic in the development community, Rust definitely holds up to the competition. Like C++, Rust compiles to native machine code and gives the developer nuanced control over system resources. It shares some optimization techniques with modern C++ compilers, while its abstractions like iterators, pattern matching, and closures are light enough to not cause runtime overhead. As a result, Rust can match or exceed C++ in many benchmarks.

Concurrency is another area where Rust improves on C++. While C++ supports multithreading, developers are responsible for its safety. Instead of relying on runtime checks or external tools, Rust catches concurrency bugs during compilation, making it safer to write parallel programs from the start.

These new mechanisms create a learning curve for developers who want to adopt Rust, but they pay off in long-term code quality and reduced maintenance costs.

Let’s take a closer look at key features of Rust and C++. In the next sections, we’ll compare how these languages perform and ensure data safety.

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Memory safety and management features

Both C++ and Rust allow fine-grained control over memory, but they approach safety and lifetime management in different ways. C++ relies on manual memory handling and developer discipline, supplemented by constructs like RAII and smart pointers. This model leaves room for errors like use-after-free, dangling pointers, and memory leaks.

Rust enforces memory safety through its ownership model and compile-time borrow checker. It makes developers follow strict rules on data ownership, borrowing, and sharing. This way, Rust eliminates common issues such as null pointers and data races and ensures reliable memory management.

Here’s how C++ and Rust handle key issues of memory management:

Issue	C++	Rust
Zero-cost abstraction
Preferring code duplication to abstraction due to high cost of virtual method calls	Zero-cost abstraction mechanisms allow you to avoid runtime costs when possible.	Zero-cost abstraction mechanisms allow you to avoid runtime costs when possible.
Move semantics
Move constructors may leave objects in invalid and unspecified states and cause use-after-move errors	Move constructors help you leave the source object in a valid state (yet the object shouldn’t be used in correct programs).	A built-in static analyzer disallows the use of objects after they have been moved.
	Use-after-move errors are detected at runtime using a special sentinel state.	The compiler can rely on a built-in analyzer for optimization.
	External static code analyzers can spot use-after-move errors at compile time.
Smart pointers vs null pointers
Use-after-free, double-free bugs, dangling pointers	Smart pointers and references are preferred to raw pointers.	Smart pointers and references are preferred to raw pointers.
Use-after-free, double-free bugs, dangling pointers	Manual code review can spot the use of raw pointers where smart pointers would suffice.	Raw pointers can be in safe code and dereferenced outside an unsafe block. The Rust compiler automatically detects them.
Null dereferencing errors	References are preferred to pointers and cannot be null.	References are preferred to pointers and cannot be null.
	Null dereferencing is possible even for smart pointers but is considered undefined behavior and should never be implemented.	Null references can be emulated by Option types, which require explicit null checks before use.
	Compilers assume that undefined behavior never happens, don’t produce warnings, and use this for optimization (sometimes with fatal consequences for security).	Smart pointers return Optional references and therefore require explicit checks as well.
	External static code analyzers can spot possible errors at compile time.	Raw pointers can be null, but they can only be used inside unsafe blocks. Unsafe blocks need to be carefully reviewed, but they can be found and marked automatically.
Data races
Data races (unsafe concurrent modification of data)	Good programming discipline, knowledge, and careful review are required to avoid concurrency errors.	The built-in borrow checker and Rust reference model detect and prohibit possible data races at compile time.
	External static code analyzers can spot some errors at compile time.	A novel locking API makes it impossible to misuse mutexes unsafely (though still allowing incorrect usage).
	External code sanitizers can spot some errors at runtime.
Object initialization
Uninitialized variables	Constructors of user-defined types are recommended to initialize all object fields.	All variables must be explicitly initialized before use (checked by the compiler).
	Primitive types still have undefined values when not initialized explicitly.	All types have defined default values that can be chosen instead of explicit initialization types.
	External static code analyzers can spot uninitialized variables.

Type system and abstractions

Type systems and abstraction mechanisms help developers express ideas, enforce correctness, and manage code complexity. C++ offers a flexible permissive type system with features like templates, function overloading, and runtime polymorphism via inheritance. The flexibility of this system lets developers be more creative but can lead to hard-to-define bugs and obscure error messages.

Rust provides a more rigid static type system that emphasizes code clarity and safety. Rust uses traits to define shared behavior, enabling a form of static polymorphism that avoids the overhead and risks of virtual dispatching.

Let’s take a closer look at the key features of type systems in both languages:

Issue	C++	Rust
Static (compile-time) polymorphism
Static interfaces for static polymorphism	Concepts provide this feature directly since C++20.	Traits provide a unified way of specifying both static and dynamic interfaces.
	Virtual functions and abstract classes may be used to declare interfaces.	Static polymorphism is guaranteed to be resolved at compile time.
	Virtual function calls may be optimized by particular compilers in known cases.
Adding new traits
Extending externally defined classes with new methods	Adding new methods normally requires inheritance, which can be inconvenient.	Traits can be added to and implemented for any class in any module at a later point.
Extending externally defined classes with new methods	Extending externally defined classes with new methods isn’t allowed in C++ directly. The closest analogue is a free function that takes the extending type as an argument.	Modules restrict visibility of available methods.
Typing of variables
Complex variable types become tedious to type manually	The auto and decltype keywords provide limited type inference (for expressions).	Local type inference (for a function body) allows you to explicitly specify types less frequently.
Complex variable types become tedious to type manually	C++20 allows use of concepts in lambda parameters. Lambda functions are allowed to have auto-deduced arguments, which makes them comparable to template functions.	Function declarations still require explicit types to ensure code readability.

Language constructs and syntax

Both C++ and Rust offer constructs for low-level programming, but their syntax and language design differ significantly. C++ has evolved over decades, accumulating features that provide flexibility but often result in complex and inconsistent syntax.

Rust’s syntax is modern, expressive, and purposefully restrictive in areas that often lead to bugs in C++. It provides constructs for control flow, pattern matching, and scoped variable declarations to reduce boilerplate code and encourage more explicit logic handling. While C++ allows many ways to express the same idea, Rust favors convention and consistency.

Issue	C++	Rust
Forgetting to handle all possible branches in switch statements	Code review and external static code analyzers can spot switch statements that don’t cover all possible branches.	The compiler checks that match expressions explicitly handle all possible values for an expression.

Use of standard and external libraries

Rust and C++ provide access to standard and third-party libraries, but their ecosystems and tools differ in consistency, diversity, and ease of use. C++ has a large and mature standard library, as well as decades of third-party libraries across virtually every domain. However, managing dependencies and building configurations in C++ can be complex.

Rust offers a more unified experience. Its standard library is smaller but focused, emphasizing core language features and portability. For external libraries, Rust uses Cargo, a built-in package manager and build system that simplifies dependency management, versioning, and reproducible builds. The centralized crates.io registry makes discovering, integrating, and updating libraries straightforward.

Issue	C++	Rust
Legacy design of utility types heavily used by standard library	Structured types like std::pair, std::tuple, and std::variant can replace ad-hoc structures.	Built-in composable structured types: tuples, structures, enumerations.
	Structured bindings allow convenient use of structured types.	Pattern matching allows convenient use of structured types like tuples and enumerations.
	Most of the standard library doesn’t use structured types.	The standard library fully embraces available pattern matching to provide easy-to-use interfaces.
Using existing libraries written in C and other languages	C libraries are immediately usable by C++ programs.	C libraries require Rust-specific header declarations.
	Libraries in languages other than C++ require wrappers.	Libraries in languages other than Rust require wrappers.
	Exporting a C interface requires only a simple unsafe extern declaration.	Exporting a C interface requires only a simple unsafe extern declaration.
	There’s no overhead in calling C functions from C++ or calling C++ functions from C.	There’s no overhead in calling C functions from Rust or calling Rust functions from C.

Runtime considerations

C++ has minimal runtime requirements and gives developers full control over memory, threading, and the execution model. This flexibility allows for highly optimized applications, but it also means that code safety fully depends on the developer’s skills.

Similarly to C++, Rust has no built-in garbage collector and a minimal runtime. It also enforces stricter compile-time checks to guarantee memory and thread safety, which result in longer compilation times but reduces runtime debugging and the number of issues after compilation.

Another key distinction is Rust’s focus on deterministic behavior. Features like guaranteed initialization, scoped resource management, and error handling reduce the risk of undefined behavior and runtime crashes.

Issue	C++	Rust
Internal buffer
Buffer overflow errors	Explicitly coded wrapper classes enforce range checks.	All slice types enforce runtime range checks.
Buffer overflow errors	Debugging builds of the STL can perform range checks in standard containers.	Range checks are avoided by most common idioms (e.g. range-based for iterators).
Runtime environment
Embedded and bare-metal programming have high restrictions on runtime environment	The C++ runtime is already fairly minimal, as it directly compiles to machine code and doesn’t use garbage collection.	The Rust runtime is already fairly minimal as it directly compiles to machine code and doesn’t use garbage collection.
	C++ programs can be built without the standard library with disabled exceptions and dynamic type information	Rust programs can be built without the standard library with disabled range checks, etc.

Conclusion

Both C++ and Rust are popular choices for low-level and system programming, driver and embedded development, and other tasks that require precise control over code and hardware.

Rust can help development teams prevent many issues native to C++ like data races, undefined behavior, and use of null raw pointers. The Rust language also has other distinctive features that allow programmers to achieve better software safety and performance. If you’re interested in the basics of Rust, check out our series of in-depth Rust tutorials starting from part one. You can also learn how to use asynchronous programming in Rust.

The Apriorit team has mastered both C++ and Rust. We’ll be glad to help you assess which is better suited for your project — or help you find the combination of C++ and Rust that works best in your conditions. We’ll also provide you with experienced development teams and niche specialists to help you start your development project without the hassle of building an in-house team from scratch.

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