rust

Local Documentation

  • rustup doc brings up all the local documentation including
    • The Rust book
    • Rust by Example
    • Cargo book
  • Inside your project, cargo doc --open opens your project's documentation
    • Without --open will just generate the documentation, which can be potentially shared with others as required.

Data Types

  • Arrays : Fixed size
    • When defining say days of the week, months of the year etc.
    • Initialize as :
      • let a = [3; 5]; is same as let a = [3, 3, 3, 3, 3];
  • Vector : Like array but can shrink and/or grow
  • If unsure, use Vector
  • Use new() or vec! to create
let mut numbers: Vec<i32> = Vec::new();
let mut magic_numbers = vec![7i32, 42, 47, 45, 54];
  • push to add at the end, pop remove from the end

Control Flow

  • rust does not have truthy values. e.g. if x is 1, then if x does not compile. x must be boolean

  • loop can have optional label. See the documentation

'outer: loop {
.   ...
  loop {  // inner, unlabeled loop
    ...
    if some_condition {
      break; // Will break from inner/unlabeled loop
    }
    ...
    ...
    if some_other_condition {
      break 'outer'; // will break out of the outer loop
    }
    ...
  }
}

Statements Vs Expressions

Statements do not return a value, expressions do.

C and Ruby, where the assignment returns the value of the assignment.
In those languages, you can write x = y = 6 and have both x and y have
the value 6; that is not the case in Rust.

In a function, last expression is also a return value.

If you add a semicolon to the end of an expression, you turn it into
a statement, and it will then not return a value.

Ownership

  • Cloning avoids Moves
  • Useful when we need to reference the "original" data after it the ownership is moved
  • .clone create a copy (which is used to move the oownership,leaving the original intact)

Slice

We create slices using a range within brackets by specifying
[starting_index..ending_index], where starting_index is the first position
in the slice and ending_index is one more than the last position in the slice.

Generics

struct State<T> {
    data: T,
}

let state_int: State<i32> = State { data: 5 };  // State holding an integer
let state_str: State<&str> = State { data: "hello" };  // State holding a string

Here State is a generic type. Defining it as State<i32> makes it specific