Introduction on RUST and C++

Rust is a system-level programming language that anchors on speed, safety, memory, and parallelism. It is syntactically comparable to C++, but it maintains high performance by providing better memory safety. Rust is a Mozilla product, and it is made open-source, which helps a wide range of developers to use it. The developers are using rust up to build a variety of new software applications, such as file systems, game engines, browser components, operating systems, virtual reality simulation engines, etc.

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C++ is one of the most accepted programming languages globally, and nowadays, it can be found in most of today’s Graphical User Interfaces, operating systems, games, and embedded systems. C++ uses the object-oriented approach, which gives us a clear view of the programs’ complexity and allows us to reuse our code, resulting in better readability and less economic development costs. Furthermore, C++ is easy to use and portable, which can be used to develop applications based on multiple platforms such as Windows, Linux, UNIX, Mac, etc.

Head to Head differences between Rust and C++(Infographics)

Given below are the top differences between Rust vs C++:

Key Difference of Rust and C++

Both Rust and C++ are popular choices in the market. Let’s discuss some of the major differences:

1. Move semantics

Moving constructor results in invalid objects with unspecified states, causing errors due to using a moving object. After an object has been moved in Rust, its state is changed to unusable by the static analyzer (built-in). All the optimizations are tagged to the analyzer (built-in), making the compiler free from it. Whereas in C++, Errors due to using of a moving object can be spotted by static code analyzers (external) at compile time. A special sentinel state is used to detect these errors at runtime.

2. Secure Memory Usage

Check on free variables usage, dangling pointers, etc. In Rust, tools can be used to find raw pointers used inside unsafe blocks. Whereas in C++, Raw pointers can only be spotted up in code review done manually, whereas smart pointers are simple to track.

3. Secure Memory Usage

Null dereferencing errors. In Rust, option types can emulate null references, which need null checks explicitly before use. Smart pointers return optional references; hence they also require explicit checks. Raw pointers can be made null only when they are used inside unsafe blocks. Whereas in C++, even for smart pointers, null dereferencing is possible; hence it should be avoided since it is considered as undefined behaviour. Compiler in C++ will never catch up with warnings or errors on such issues. But compile-time errors can be caught by static code analyzers (external).

4. Secure Memory Usage

Errors caused due to buffer overflow. In Rust, range checks are automatically enforced on all slice types at runtime. Whereas in C++, range checks can be enforced by wrapper classes which must be explicitly introduced in the code.

5. No data race between Threads

Modification of concurrent data( unsafely ). In Rust, possible inconsistency can be traced by the rust reference model and built-in borrow checker at compile time. Unsafe Misuse of mutexes can be made impossible by locking API unsafely. Whereas in C++, some errors can be spotted by static code analyzers (external) at the time of compilation. Good knowledge, careful review, and programming discipline are necessary for avoiding concurrency errors. Some errors can be spotted by code sanitizers (external) at runtime.

6. Object initialization

Initialization of variables. In Rust, any variable created in Rust Program should be initialized. ( else results in a compiler error). All the types in Rust have some default defined values. Whereas in C++, uninitialized variables can be spotted by static code analyzers (external). If not initialized, objects of any primitive types will result in undefined values.

7. Pattern matching

Each branch of a switch statement should be properly handled, or if not handled then, what?. In Rust, each and every possible value of a pattern is ensured in Rust; otherwise, it won’t compile. Whereas in C++, Each and every possible branch of the switch statement can be spotted by static code analyzers (external) and Code review.

8. Static (compile-time) Polymorphism

Sometimes to achieve compile-time polymorphism, static interfaces are used. In Rust, both the static and dynamic interfaces have been specified in a united way by Traits. All compile-time polymorphism is ensured to be resolved on compile-time in Rust. Whereas in C++, some compilers may optimize calls of the virtual function in some known cases. Interfaces are declared using abstract classes and virtual functions.

9. Type Inference

It is very tedious to type some of the (complex) variable types manually. In Rust, explicit types are required by function declarations which ensure good readability of the program. Inside a function body in Rust, (Local) Type Inference allows us to specify types explicitly less frequently. Whereas in C++, The decltype & auto keywords provide a limited type of type inference ( for the code’s expressions).

10. Macros

In Rust, the Syntax to define macros in Rust is macros_rules!. Whereas in C++,Syntax to define a macros in C++ is #define

11. Standard library

The standard library makes the most of the utility type’s legacy design. In Rust, tuples, enumerations, structures form some of the built-in structured types of Rust. The standard library is fully utilizing all the available pattern matching to provide foolproof Interfaces. Whereas in C++, Ad-hoc structures can replace structured types such as std:: variant, std:: tuple, and std:: pair.

Comparison Table of Rust vs C++

The comparison table has been explained below:

Key factors	Rust	C++
Zero overhead abstraction Zero overhead abstraction is a functionality that is present in the source code but still does not have any overhead on the compiled object code.	A zero-overhead abstraction can be achieved.	A zero-overhead abstraction can be achieved.
Secure Memory Usage Check on free variables usage, dangling pointers, etc.	Smart pointers are preferred over raw pointers.	Smart pointers are preferred over raw pointers.
Secure Memory Usage Null dereferencing errors	Pointers should be used for reference, and they should not be null.	Pointers should be used for reference, and they should not be null.
No data race between Threads Modification of concurrent data( unsafely )	It can result in deadlocks.	It can result in deadlocks.
Runtime environment High restrictions have been imposed by bare-metal or embedded programming on runtime.	• Rust directly compiles the program into machine language, which makes its runtime reasonably low, and it does not support garbage collection. • Programs in C++ can be made (without the use of standard libraries) by disabling the range checks, etc.	• C++ directly compiles the program into machine language, which makes its runtime reasonably low, and it does not support garbage collection. • Programs in C++ can be made (without using standard libraries) by dynamic type info, disabled exceptions, etc.
Efficient C bindings Usage of existing libraries of C or any other language.	• Requires wrappers for libraries in other languages. • A simple extern declaration is all that is needed to export a C interface. • No overhead while calling C functions in Rust.	• Requires wrappers for libraries in other languages. • A simple extern declaration is all that is needed to export a C interface. • No overhead while calling C functions in C++.

Conclusion

Rust is a modern-day new programming language that has a similar coding structure as C++, but it is faster and more secure with simple built-in methods to be used.

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