206 lines
4.2 KiB
Markdown
206 lines
4.2 KiB
Markdown
# Rustposting
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Some example code with some potential problem characters:
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```rust
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let newline_string = "hello \n world";
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let thing = *newline_string;
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```
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Here is some example rust code:
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```rust
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fn main() {
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// Statements here are executed when the compiled binary is called.
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// Print text to the console
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println!("Hello World!");
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}
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```
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And a slightly less trivial example:
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```rust
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fn main() {
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// Variables can be type annotated.
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let logical: bool = true;
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let a_float: f64 = 1.0; // Regular annotation
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let an_integer = 5i32; // Suffix annotation
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// Or a default will be used.
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let default_float = 3.0; //
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let default_integer = 7; //
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// A type can also be inferred from context.
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let mut inferred_type = 12; // Type i64 is inferred from another line.
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inferred_type = 4294967296i64;
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// A mutable variable's value can be changed.
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let mut mutable = 12; // Mutable
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mutable = 21;
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// Error! The type of a variable can't be changed.
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mutable = true;
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// Variables can be overwritten with shadowing.
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let mutable = true;
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/* Compound types - Array and Tuple */
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// Array signature consists of Type T and length as [T; length].
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let my_array: [i32; 5] = [1, 2, 3, 4, 5];
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// Tuple is a collection of values of different types
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// and is constructed using parentheses ().
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let my_tuple = (5u32, 1u8, true, -5.04f32);
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}
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```
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Toss in some type definitions to
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```rust
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#[derive(Debug)]
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struct Person {
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name: String,
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age: u8,
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}
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// A unit struct
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struct Unit;
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// A tuple struct
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struct Pair(i32, f32);
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enum WebEvent {
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// An variant may either be
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PageLoad,
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PageUnload,
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// like tuple structs,
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KeyPress(char),
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Paste(String),
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// or c-like structures.
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Click { x: i64, y: i64 },
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}
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struct Point {
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x: f64,
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y: f64,
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}
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// Implementation block, all associated functions & methods go in here
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impl Point {
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// This is an "associated function" because this function is associated with
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// a particular type, that is, Point.
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//
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// Associated functions don't need to be called with an instance.
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// These functions are generally used like constructors.
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fn origin() -> Point {
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Point { x: 0.0, y: 0.0 }
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}
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// Another associated function, taking two arguments:
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fn new(x: f64, y: f64) -> Point {
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Point { x: x, y: y }
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}
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}
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```
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Modules and imports
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```rust
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#![allow(unused_variables)]
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use deeply::nested::function as other_function;
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use std::fs::File;
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fn function() {
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println!("called function()");
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}
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mod deeply {
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pub mod nested {
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pub fn function() {
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println!("called deeply::nested::function()");
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}
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}
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}
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struct Val {
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val: f64,
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}
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struct GenVal<T> {
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gen_val: T,
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}
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// impl of Val
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impl Val {
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fn value(&self) -> &f64 {
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&self.val
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}
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}
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impl<T> GenVal<T> {
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fn value(&self) -> &T {
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&self.gen_val
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}
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}
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let a = Box::new(5i32);
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macro_rules! say_hello {
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() => {
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// The macro will expand into the contents of this block.
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println!("Hello!")
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};
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}
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macro_rules! calculate {
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(eval $e:expr) => {
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{
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let val: usize = $e; // Force types to be unsigned integers
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println!("{} = {}", stringify!{$e}, val);
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}
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};
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}
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fn give_adult(drink: Option<&str>) {
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// Specify a course of action for each case.
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match drink {
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Some("lemonade") => println!("Yuck! Too sugary."),
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Some(inner) => println!("{}? How nice.", inner),
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None => println!("No drink? Oh well."),
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}
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}
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impl Person {
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// Gets the area code of the phone number of the person's job, if it exists.
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fn work_phone_area_code(&self) -> Option<u8> {
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// It would take a lot more code - try writing it yourself and see which
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// is easier.
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self.job?.phone_number?.area_code
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}
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}
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#[cfg(target_family = "unix")]
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#[link(name = "m")]
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extern {
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// this is a foreign function
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// that computes the square root of a single precision complex number
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fn csqrtf(z: Complex) -> Complex;
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fn ccosf(z: Complex) -> Complex;
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}
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fn main() {
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let raw_p: *const u32 = &10;
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unsafe {
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assert!(*raw_p == 10);
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}
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}
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```
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