Index

Rust

  1. Guessing Game
  2. Common Programming Concepts
    1. Variables and Mutability
    2. Data Types
    3. Function
    4. Control Flow
  3. Understanding Ownership
    1. References and Borrowing
    2. The Slice Type
  4. Using Structs
    1. An Example Program Using Structs
    2. Method Syntax
  5. Enums and Pattern Matching
    1. The match Control Flow Operator
    2. Concise Control Flow with if let
  6. Managing Growing Projects with Packages, Crates, and Modules
    1. Defining Modules to Control Scope and Privacy
    2. Paths for Referring to an Item in the Module Tree
    3. Bringing Paths into Scope with the use Keyword
    4. Separating Modules into Different Files
  7. Common Collections
    1. Storing UTF-8 Encoded Text with Strings
    2. Storing Keys with Associated Values in Hash Maps
  8. Error Handling
    1. Unrecoverable Errors with panic!
    2. Recoverable Errors with Result
  9. Generic Types, Traits, and Lifetimes
    1. Traits: Defining Shared Behavior
    2. Generics Rust by Example
      1. Functions
      2. Implementation
  10. Writing Automated Tests
  11. Object Oriented Programming
  12. Adding dependancies
  13. Option Take
  14. RefCell
  15. mem
  16. Data Structure
    1. Linked List
    2. Binary search tree
    3. N-ary Sum tree
  17. Recipe
    1. Semi colon
    2. Calling rust from python
    3. Default
    4. Crytocurrency With rust
    5. Function chaining
    6. Question Mark Operator
    7. Tests with println
    8. lib and bin
    9. Append vector to hash map
    10. Random Number
    11. uuid4
    12. uwrap and option
  18. Blockchain with Rust
  19. Near Protocol
    1. Startup code
    2. Couter
    3. Status
    4. Avrit
  20. Actix-web

Control Flow

Control Flow

if

Expressions


fn main() {
    let number = 3;

    if number < 5 {
        println!("condition was true");
    } else {
        println!("condition was false");
    }
}


Blocks of code associated with the conditions in if expressions are sometimes called arms, just like the arms in match expression

Error code:
expected `bool`, found integer
fn main() {
    let number = 3;

    if number {
        println!("number was three");
    }
}


Using

if

in a

let

Statement


fn main() {
    let condition = true;
    let number = if condition { 5 } else { 6 };

    println!("The value of number is: {}", number); //The value of number is: 5
}


Error code:
fn main() {
    let condition = true;

    let number = if condition { 5 } else { "six" };

    println!("The value of number is: {}", number);
}

$ cargo run
   Compiling branches v0.1.0 (file:///projects/branches)
error[E0308]: if and else have incompatible types
 --> src/main.rs:4:44
  |
4 |     let number = if condition { 5 } else { "six" };
  |                                 -          ^^^^^ expected integer, found `&str`
  |                                 |
  |                                 expected because of this

error: aborting due to previous error

For more information about this error, try `rustc --explain E0308`.
error: could not compile `branches`.

To learn more, run the command again with --verbose.


Repeating Code with

loop


fn main() {
    loop {
        println!("again!");
    }
}


Returning Values from Loops


fn main() {
    let mut counter = 0;

    let result = loop {
        counter += 1;

        if counter == 10 {
            break counter * 2;
        }
    };

    println!("The result is {}", result); // The result is 20
}


Conditional Loops with while
fn main() {
    let mut number = 3;

    while number != 0 {
        println!("{}!", number);

        number -= 1;
    }

    println!("LIFTOFF!!!");
}


Looping Through a Collection with for
fn main() {
    let a = [10, 20, 30, 40, 50];

    for element in a.iter() {
        println!("the value is: {}", element);
    }
}


Here’s what the countdown would look like using a for loop and another method we’ve not yet talked about, rev, to reverse the range:
fn main() {
    for number in (1..4).rev() {
        println!("{}!", number);
    }
    println!("LIFTOFF!!!");
}