Material source: The Rust Programming Language Book

Common Commands

• cargo new app
  • Creates a new rust project in the designated dir
• cargo build
  • Builds a debug version of the app in ./target/debug
• cargo build --release
  • Builds a release version of the app in ./target/release
• cargo run
  • Builds and runs the app
• cargo update
  • Updates any dependencies to the most recent non-BC version (0.8.3 --> 0.8.4, but NOT 0.8.3 --> 0.9.0)
• cargo check
  • Performs a syntax check on all the app code, but does not build the app
• cargo doc --open
  • Creates documentation for the app and any dependencies

Common Actions

• To add a dependency
  • add it to Cargo.toml in the dependencies section

Fundamentals

• Variables default to immutable
  • To declare a variable as mutable
    • let mut x = 5;
• To explicitly cast a variable type
  • let x: u32 = 23423;
• Constants must have their type declared explicitly
  • Cannot be set via runtime, it but be a pre-defined value
  • ex: const THREE_HOURS_IN_SECONDS: u32 = 60 * 60 * 3;
• Shadowing variables allows you to change the value of variable, but only in the specific scope
• Character type is denoted with single quotes (Unicode Scalar Value)
  • let my_char = 'C';
• String type is denoted with double quotes
  • let my_sentence = "This is my sentence";
• Compound Types
  • Tuple
    • Fixed length on creation
    • let my_tup: (u32, f64, i32) = (34523, 82323.3382, -3432);
    • let (x, y, z) = my_tup;
    • println!("The value of y is: {}", y);
    • OR
    • println!("The value of the second element is: {}", my_tup.1);
    • Empty Tuples is a unit_type and the value is a unit_value, expressed as ()
  • Array
    • Fixed length on creation
    • All elements must be the same type
    • let my_array = [1, 3, 10, 1];
    • Vector is similar to an array, but have variable sizing
    • let my_new_array: [u32, 4] = [1, 39, 9, 129834];
    • Accessing array elements
    • let my_second_element = my_new_array[0];
• Functions
  • Defined with fn the function name, parentheses and curly brackets
    • fn my_function() {}
  • Parameter/argument in function call
    • Parameters must have type declaration
    • fn my_function(x: i32) { println!("The value of x is: {}", x); }
    • fn print_labeled_measurement(value: i32, unit_label: char) { println!("The measurement is {}{}", value, unit_label); }
  • Expressions do not end in a semi-colon, if it does, it turns into a statement and does not return a value
  • ex: let y = { let x = 3; x + 1 };
  • y evaluates to 4, if a semi-colon was added to the end of x + 1, y would not be 4
  • Return type of a function is declared with an ->
  • fn five() -> i32 { 5 }