rustlearningbymyself

Rust learning notes

1. Day

   First of all, i started to learn Rust by myself and wrote a hello-world program as all beginner did. Then according to the book from Rust homepage i developed a guess-number rust-program.

2. Day

   Data types learning: Integer types with signed and unsigned, floating-point types boolean, character as well as tuple and array as compound types. Array in Rust has a fixed length, also tuple.

   Ownership rules in rust:

   • Each value in Rust has a variable that’s called its owner.

   • There can only be one owner at a time.

   • When the owner goes out of scope, the value will be dropped.

   Borrowing rule:

   • We cannot have a mutable reference while we have a immutable one.

   • Multi mutable references are not acceptable in a scope, but immutable reference are acceptable.

   • References must always be valid

   • string literal and &str are immutable

3. Day

   Struct learning: #[derive(Debug)] could give struct a character. For example Debug could let the struct print by {:?}.

   match or if let can be used, when enum values have data inside them.

   Vec<T> is likely a mutable list. Vec::new() creates a leer list or vec![1,2,3] a list with elements 1, 2, 3. push is the update method for list. &v[2] or v.get(2) can read a element of vectors but get returns Option<&T>.

   String is mutable but str not. push_str(&str) appends a string to another.

   HashMap stores a mapping of keys to values. let my_hashmap: HashMap<_, _> = vec1_keys.iter().zip(vec2_values.iter()).collect(); creates a hashmap from two vectors.

4. Day

   Error handling: the ? Operator can only be used in functions that return Result. The decision on panic! or Result depends on, if an error should be recovered or not. In most situation Result should be used because we do not want the program to crush. It should be fixed.

   Using panic! and Result in the appropriate situation will make my code more reliable in the face of inevitable problems.

5. Day

   generic Type in rust, we pay no runtime cost for using it, because rust compiles generic code into code that specifies the type in each instance. When the code runs, it performs just as it would if we had duplicated each definition by hand.

   Definition of a Trait is a way to group method signatures together to define a set of behaviors necessary to accomplish some purpose.

   the main aim of lifetimes is to prevent dangling references, which cause a program to reference data other than the data it's intended to reference. lifetime's notation do not change the lifetime, it helps compiler to check if a reference is valid.