Introduction to Rust Programming Language - GeeksforGeeks

23 Nov, 2021
Rust is a blazing fast and memory-efficient static compiled language with a rich type system and ownership model. It can be used to power performance-critical services while guaranteeing memory-safety and thread-safety, empowering developers to debug at compile-time. In addition to that Rust has great documentation and a user-friendly compiler with top-end tools like integrated package managers and multi-editor with features like type inspection and auto-completion. Rust prevents all the crashes, and it is very interesting that rust is safe by default like JavaScript, Ruby, and Python. This is much powerful than C/C++ because we cannot write the wrong parallel code you can never see fault in rust. It is very fast in representing a lot of programming paradigms very well. 
But the question arises as there are already so many programming languages like Python, C++, Java, etc, then why the need for developing a new programming language. The answer to this is the other programming language has a lot of control over the hardware that you are running, like, you can optimize it well, translate directly to assembly code, But it’s not very safe.
So rust provides us all the controls that we can have and all the levels of security that we can achieve.
Rust is using Rust which means the all the standard compiler the libraries are written in rust, there is a bit of use of C programming language but most of them is Rust. The big project of Rust is “servo”,  It is a project to write out the totally parallel layout engine like things like a gecko as Firefox or WebKit in safari.
Servo built the layout engine something to render HTML from bottom to top.
Functions are the block of reusable code that can perform similar related actions. You have already seen one of the most important functions in the language: the main function, which is the entry point of many programs. You’ve also seen the “fn” keyword, which allows you to declare new functions. Rust code uses snake case as the conventional style for function and variable names. In snake case, all letters are lowercase and underscore separate words.
Syntax:
fn functionname(arguments){
  code
}
To create a function we need to use the fn keyword.
The function name is written after the fn keyword
Arguments are passed after function name inside parenthesis
You can write function code in function block
Example: The below function simply prints “Hello, World!” in the console:
Rust
fn main() {   println!("Hello, world!");}
Output:
Hello, World!
The concept of ownership is that when you own something you can decide to pass it to someone else, if you have a book, and you have done reading it you can permanently give it to someone and not worry about it. 
Rust
fn helper() -> Box<int> {let three = box 3;return three; //transfer ownership}fn main() {// acquire ownership of return valuelet my_three = helper();}
Owned values in rust can be borrowed to allow usage for a certain period of time The “&” sign represents the borrowed reference. Borrowed values have a lifetime and are valid for that time only. Borrowing prevents moving. While there is an active borrow I can not transfer ownership. I still own it but cannot transfer it until I handed it in to really relinquish that borrowed. 
Rust
let a: &int;{let b =3; //b lifetime is not same as aa =&b;}  //
Here “a” and “b” has a different lifetime, so it will not work.
Rust
let a: &int;let b=3;  // a and b have same lifetimea = &b;
Here “a” and “b” have the same life, so it will work. Borrow can be nested. Through cloning, borrowed values can become owned.
Rust has fine-grain memory management but is automatically managed once created.In Rust when you allocate memory you never have to really free it you can decide when to free it but never call it. Rust takes care of it automatically.Each variable has a scope it is valid for, and it gets automatically deallocated once it goes out of scope.In rust, each program is allocated memory from the operating system.Rust also has a shared memory where we can have a reference piece of data, we can use ownership to keep track of reference count.
Rust has fine-grain memory management but is automatically managed once created.
In Rust when you allocate memory you never have to really free it you can decide when to free it but never call it. Rust takes care of it automatically.
Each variable has a scope it is valid for, and it gets automatically deallocated once it goes out of scope.
In rust, each program is allocated memory from the operating system.
Rust also has a shared memory where we can have a reference piece of data, we can use ownership to keep track of reference count.
Heap:
It is the biggest memory block and is managed by the rust ownership model.
At this place, all the dynamic data is stored.
Stack:
All values in rust are allocated on the stack.
At this, the static memory is allocated by default.
There is one stack per thread.
It includes structures and pointers to dynamic data.
Values in rust are immutable by default and must be tagged as being mutable(if needed).
Example:
Rust
let x = 2;x = 9; //it will show an error
The above example will show an error because we have not tagged it as mutable.
Rust
let mut x = 2;x = 9;  //work correctly
This will work fine as we have tagged it as being mutable. As in this case we are explicitly mutating it.
The structure is a user-defined data type in rust that is used to combine different data items of a different type. Structure defines data as a key-value pair. The struct keyword is used to define Structures in Rust.
Syntax: 
struct Name_of_structure {
  field1:data_type,
  field2:data_type,
  field3:data_type
}
Example:
Rust
struct Employee {  name: String,  company: String,  employee_id: u32,  profile: String }fn main() {  let value = Employee {    name: String::from("Geek"),    company: String::from("Geeksforgeeks.org"),    employee_id: 007,    profile:String::from("Manager"),   };  println!("Employee: {} of {} Company bearing EmployeeID {} is of {} level.",    value.name,    value.company,    value.employee_id,    value.profile);}
Output:
Employee: Geek of Geeksforgeeks.org Company bearing EmployeeID 7 is of Manager level.
This is an example of how we create structures in rust. This will compile perfectly.
A tuple in rust is a finite heterogeneous compound data type, meaning it can store more than one value at once. In tuples, there is no inbuilt method to add elements into a tuple. We can use the index to get the value of a tuple, and we also can not iterate over a tuple using for loop.
Tuples in Rust are defined using small brackets as shown below :
Syntax: ("geeksforgeeks", 1, 'geek')
Example:
Rust
// Rust program to get value from tuple// using indexfn main() {    let gfg = ("cp", "algo", "FAANG", "Data Structure");          // complete tuple    println!("complete tuple = {:?} ", gfg );          // first value    println!("at 0 index = {} ", gfg.0 );          // second value    println!("at 0 index = {} ", gfg.1 );          // third value    println!("at 0 index = {} ", gfg.2 );          // fourth value    println!("at 0 index = {} ", gfg.3 );}
Output:
complete tuple = ("cp", "algo", "FAANG", "Data Structure") 
at 0 index = cp 
at 0 index = algo 
at 0 index = FAANG 
at 0 index = Data Structure 
In Rust, every variable, value, and item has a type. The type defines how much memory it is holding and which operation can be performed on the value. The below table states all the types in Rust:
Advantages:
Quick debugging and testing: Rust is a very fast language and supports quick and effective debugging.Rust supports more complex code as compared to other languages, so we can achieve more in less code.It enables cross-platform development.Ease of integration: Rust can be easily integrated with C and many other famous programming languages.Rust is safer than other programming languages.There is a wide community of developer which support Rust.
Quick debugging and testing: Rust is a very fast language and supports quick and effective debugging.
Rust supports more complex code as compared to other languages, so we can achieve more in less code.
It enables cross-platform development.
Ease of integration: Rust can be easily integrated with C and many other famous programming languages.
Rust is safer than other programming languages.
There is a wide community of developer which support Rust.
Disadvantages:
Due to complexity, it may take a longer time to learn Rust.In rust, code can be less efficient and also it takes more time to compile.As it is more complex, so it may take more time to complete apps written in Rust.It is a new language, so it will take more time to spread over and jobs in rust also may not be as much as in other popular programming languages.In some cases, rust can leak memory and become slower than a popular programming language.
Due to complexity, it may take a longer time to learn Rust.
In rust, code can be less efficient and also it takes more time to compile.
As it is more complex, so it may take more time to complete apps written in Rust.
It is a new language, so it will take more time to spread over and jobs in rust also may not be as much as in other popular programming languages.
In some cases, rust can leak memory and become slower than a popular programming language.
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Rust - Casting
Rust - For and Range
Rust - Generic Function
Rust - References & Borrowing
Rust - While Loop
Rust - Box Smart Pointer
Rust - Concept of Structures
Primitive Compound Datatypes in Rust
Rust - Recoverable Errors
Rust - Concept of Smart Pointers