notes

class/notes

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+why printf is a macro
+
+println works like printf
+"{}" placeholders are subed with vars
+
+so
+
+printlin takes a variable number of args
+rust functions don't support overloading, or take variable number of arguments.
+
+macros can generate the functions with the number of called arguments
+
+
+the collatz conjecture
+
+rust infers types
+print macro doesn't add \n!!!!
+
+print/ln also can put var inside the "{}" string interpolation ftw!
+
+doc: std.rs/
+
+&thing
+
+say: ref-thing
+
+defining var without a value is uninitialized
+access is an error
+
+use default value:
+
+let var = bool::default();
+
+arrays! [T; N]
+[20, 30, 40]
+[0; 3] // three elements, all elements are 0
+
+fixed contiguous chunk of memory
+same type
+
+slices!
+variable contiguous chunk of memory
+same type
+
+&[T]
+&array[0..5]
+
+tuples!
+fixed length, different types
+
+let t = (7, true);
+
+empty tuple: ()
+called: unit
+
+
+dot syntax
+
+t.0;
+t.1;
+
+
+debug print
+
+"{:?}" // use debug representation
+
+
+references:
+
+let mut x = 10;
+let ref_x: &mut i32 = &mut x;
+let ref_x = &mut x; // same thing
+
+*ref_x = 20;
+
+
+let a = [10, 20, 30, 40, 50];
+println!("a: {a:$?}");
+let s: &[i32] = &a[2..4];
+println!("a: {a:$?}");
+
+mutability xor sharability
+
+String vs str (also a dozen more)
+
+two core types:
+
+&str (ref str) borrowed utf-8 chunks of data
+so you can't append
+
+String (part of std)
+you want to own your string data, and be able to resize
+
+vec dynamic array you can push and pop
+
+range syntax:
+  for i in 1..=n { // include the last element
+  for i in 1..n { // up to the last element
+
+  }
+
+
+match is kinda like switch:
+
+match (thing, anotther thing) {
+  (true, true) => res,
+  (true, false) => res2,
+  _ => default case,
+}
+
+match is exhaustive by compiler directive!
+
+
+
+last expression returns a value
+
+arrow syntax to define return type of function
+idiomatic return is to leave out return keyword and semicolon
+
+"function returns unit" means the function doesn't return anything
+
+default return is unit
+
+docs.rs // docs for crate
+rustdoc 
+
+
+methods!
+
+functions associated with a particular type
+
+struct Rectangle {}
+
+impl Rectangle {
+  fn area(&self) -> u32 { //first arg is always either
+                          // self
+                          // &self
+                          // &mut self
+  }
+}
+
+borrow completes at the end of block - easy mode
+
+the compiler will put something out of scope when it's not used anymore
+
+functions:
+  no default args
+  no function overloading
+  function parameter can be generic
+
+available on line: comprehensive rust
+
+go/comprehensive-rust-material
+
+type conversions x as i16 etc.
+
+traits!
+type conversions in a generic way
+x.into() will do the type conversion for you, if valid and lossless
+