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| author | Alex Crichton <alex@alexcrichton.com> | 2014-01-28 12:01:57 -0800 |
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| committer | Alex Crichton <alex@alexcrichton.com> | 2014-02-02 10:59:14 -0800 |
| commit | 864b434bfa3fd5b3ea9e38958652ed1abdc24f1d (patch) | |
| tree | 55d1693b52303c3ae620762f31b616663746a442 /doc/complement-cheatsheet.md | |
| parent | 2ff16b184950f5b24c3b2a4bf57b6dd7b3fbbe17 (diff) | |
| download | rust-864b434bfa3fd5b3ea9e38958652ed1abdc24f1d.tar.gz rust-864b434bfa3fd5b3ea9e38958652ed1abdc24f1d.zip | |
Move doc/ to src/doc/
We generate documentation into the doc/ directory, so we shouldn't be intermingling source files with generated files
Diffstat (limited to 'doc/complement-cheatsheet.md')
| -rw-r--r-- | doc/complement-cheatsheet.md | 214 |
1 files changed, 0 insertions, 214 deletions
diff --git a/doc/complement-cheatsheet.md b/doc/complement-cheatsheet.md deleted file mode 100644 index a92980d5e70..00000000000 --- a/doc/complement-cheatsheet.md +++ /dev/null @@ -1,214 +0,0 @@ -% Rust Cheatsheet - -# How do I convert *X* to *Y*? - -**Int to string** - -Use [`ToStr`](http://static.rust-lang.org/doc/master/std/to_str/trait.ToStr.html). - -~~~ -let x: int = 42; -let y: ~str = x.to_str(); -~~~ - -**String to int** - -Use [`FromStr`](http://static.rust-lang.org/doc/master/std/from_str/trait.FromStr.html), and its helper function, [`from_str`](http://static.rust-lang.org/doc/master/std/from_str/fn.from_str.html). - -~~~ -let x: Option<int> = from_str("42"); -let y: int = x.unwrap(); -~~~ - -**Int to string, in non-base-10** - -Use [`ToStrRadix`](http://static.rust-lang.org/doc/master/std/num/trait.ToStrRadix.html). - -~~~ -use std::num::ToStrRadix; - -let x: int = 42; -let y: ~str = x.to_str_radix(16); -~~~ - -**String to int, in non-base-10** - -Use [`FromStrRadix`](http://static.rust-lang.org/doc/master/std/num/trait.FromStrRadix.html), and its helper function, [`from_str_radix`](http://static.rust-lang.org/doc/master/std/num/fn.from_str_radix.html). - -~~~ -use std::num::from_str_radix; - -let x: Option<i64> = from_str_radix("deadbeef", 16); -let y: i64 = x.unwrap(); -~~~ - -# File operations - -## How do I read from a file? - -Use [`File::open`](http://static.rust-lang.org/doc/master/std/io/fs/struct.File.html#method.open) to create a [`File`](http://static.rust-lang.org/doc/master/std/io/fs/struct.File.html) struct, which implements the [`Reader`](http://static.rust-lang.org/doc/master/std/io/trait.Reader.html) trait. - -~~~ {.ignore} -use std::path::Path; -use std::io::fs::File; - -let path : Path = Path::new("Doc-FAQ-Cheatsheet.md"); -let on_error = || fail!("open of {:?} failed", path); -let reader : File = File::open(&path).unwrap_or_else(on_error); -~~~ - -## How do I iterate over the lines in a file? - -Use the [`lines`](http://static.rust-lang.org/doc/master/std/io/trait.Buffer.html#method.lines) method on a [`BufferedReader`](http://static.rust-lang.org/doc/master/std/io/buffered/struct.BufferedReader.html). - -~~~ -use std::io::BufferedReader; -# use std::io::MemReader; - -# let reader = MemReader::new(~[]); - -let mut reader = BufferedReader::new(reader); -for line in reader.lines() { - print!("line: {}", line); -} -~~~ - -# String operations - -## How do I search for a substring? - -Use the [`find_str`](http://static.rust-lang.org/doc/master/std/str/trait.StrSlice.html#tymethod.find_str) method. - -~~~ -let str = "Hello, this is some random string"; -let index: Option<uint> = str.find_str("rand"); -~~~ - -# Containers - -## How do I get the length of a vector? - -The [`Container`](http://static.rust-lang.org/doc/master/std/container/trait.Container.html) trait provides the `len` method. - -~~~ -let u: ~[u32] = ~[0, 1, 2]; -let v: &[u32] = &[0, 1, 2, 3]; -let w: [u32, .. 5] = [0, 1, 2, 3, 4]; - -println!("u: {}, v: {}, w: {}", u.len(), v.len(), w.len()); // 3, 4, 5 -~~~ - -## How do I iterate over a vector? - -Use the [`iter`](http://static.rust-lang.org/doc/master/std/vec/trait.ImmutableVector.html#tymethod.iter) method. - -~~~ -let values: ~[int] = ~[1, 2, 3, 4, 5]; -for value in values.iter() { // value: &int - println!("{}", *value); -} -~~~ - -(See also [`mut_iter`](http://static.rust-lang.org/doc/master/std/vec/trait.MutableVector.html#tymethod.mut_iter) which yields `&mut int` and [`move_iter`](http://static.rust-lang.org/doc/master/std/vec/trait.OwnedVector.html#tymethod.move_iter) which yields `int` while consuming the `values` vector.) - -# Type system - -## How do I store a function in a struct? - -~~~ -struct Foo { - myfunc: fn(int, uint) -> i32 -} - -struct FooClosure<'a> { - myfunc: 'a |int, uint| -> i32 -} - -fn a(a: int, b: uint) -> i32 { - (a as uint + b) as i32 -} - -fn main() { - let f = Foo { myfunc: a }; - let g = FooClosure { myfunc: |a, b| { (a - b as int) as i32 } }; - println!("{}", (f.myfunc)(1, 2)); - println!("{}", (g.myfunc)(3, 4)); -} -~~~ - -Note that the parenthesis surrounding `f.myfunc` are necessary: they are how Rust disambiguates field lookup and method call. The `'a` on `FooClosure` is the lifetime of the closure's environment pointer. - -## How do I express phantom types? - -[Phantom types](http://www.haskell.org/haskellwiki/Phantom_type) are those that cannot be constructed at compile time. To express these in Rust, zero-variant `enum`s can be used: - -~~~ -enum Open {} -enum Closed {} -~~~ - -Phantom types are useful for enforcing state at compile time. For example: - -~~~ -struct Door<State>(~str); - -struct Open; -struct Closed; - -fn close(Door(name): Door<Open>) -> Door<Closed> { - Door::<Closed>(name) -} - -fn open(Door(name): Door<Closed>) -> Door<Open> { - Door::<Open>(name) -} - -let _ = close(Door::<Open>(~"front")); -~~~ - -Attempting to close a closed door is prevented statically: - -~~~ {.ignore} -let _ = close(Door::<Closed>(~"front")); // error: mismatched types: expected `main::Door<main::Open>` but found `main::Door<main::Closed>` -~~~ - -# FFI (Foreign Function Interface) - -## C function signature conversions - -Description C signature Equivalent Rust signature ----------------------- ---------------------------------------------- ------------------------------------------ -no parameters `void foo(void);` `fn foo();` -return value `int foo(void);` `fn foo() -> c_int;` -function parameters `void foo(int x, int y);` `fn foo(x: int, y: int);` -in-out pointers `void foo(const int* in_ptr, int* out_ptr);` `fn foo(in_ptr: *c_int, out_ptr: *mut c_int);` - -Note: The Rust signatures should be wrapped in an `extern "ABI" { ... }` block. - -### Representing opaque handles - -You might see things like this in C APIs: - -~~~ {.notrust} -typedef struct Window Window; -Window* createWindow(int width, int height); -~~~ - -You can use a zero-element `enum` ([phantom type](#how-do-i-express-phantom-types)) to represent the opaque object handle. The FFI would look like this: - -~~~ {.ignore} -enum Window {} -extern "C" { - fn createWindow(width: c_int, height: c_int) -> *Window; -} -~~~ - -Using a phantom type ensures that the handles cannot be (safely) constructed in client code. - -# Contributing to this page - -For small examples, have full type annotations, as much as is reasonable, to keep it clear what, exactly, everything is doing. Try to link to the API docs, as well. - -Similar documents for other programming languages: - - * [http://pleac.sourceforge.net/](http://pleac.sourceforge.net) |
