      1
      2
      3
      4
      5
      6
      7
      8
      9
     10
     11
     12
     13
     14
     15
     16
     17
     18
     19
     20
     21
     22
     23
     24
     25
     26
     27
     28
     29
     30
     31
     32
     33
     34
     35
     36
     37
     38
     39
     40
     41
     42
     43
     44
     45
     46
     47
     48
     49
     50
     51
     52
     53
     54
     55
     56
     57
     58
     59
     60
     61
     62
     63
     64
     65
     66
     67
     68
     69
     70
     71
     72
     73
     74
     75
     76
     77
     78
     79
     80
     81
     82
     83
     84
     85
     86
     87
     88
     89
     90
     91
     92
     93
     94
     95
     96
     97
     98
     99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127
    128
    129
    130
    131
    132
    133
    134
    135
    136
    137
    138
    139
    140
    141
    142
    143
    144
    145
    146
    147
    148
    149
    150
    151
    152
    153
    154
    155
    156
    157
    158
    159
    160
    161
    162
    163
    164
    165
    166
    167
    168
    169
    170
    171
    172
    173
    174
    175
    176
    177
    178
    179
    180
    181
    182
    183
    184
    185
    186
    187
    188
    189
    190
    191
    192
    193
    194
    195
    196
    197
    198
    199
    200
    201
    202
    203
    204
    205
    206
    207
    208
    209
    210
    211
    212
    213
    214
    215
    216
    217
    218
    219
    220
    221
    222
    223
    224
    225
    226
    227
    228
    229
    230
    231
    232
    233
    234
    235
    236
    237
    238
    239
    240
    241
    242
    243
    244
    245
    246
    247
    248
    249
    250
    251
    252
    253
    254
    255
    256
    257
    258
    259
    260
    261
    262
    263
    264
    265
    266
    267
    268
    269
    270
    271
    272
    273
    274
    275
    276
    277
    278
    279
    280
    281
    282
    283
    284
    285
    286
    287
    288
    289
    290
    291
    292
    293
    294
    295
    296
    297
    298
    299
    300
    301
    302
    303
    304
    305
    306
    307
    308
    309
    310
    311
    312
    313
    314
    315
    316
    317
    318
    319
    320
    321
    322
    323
    324
    325
    326
    327
    328
    329
    330
    331
    332
    333
    334
    335
    336
    337
    338
    339
    340
    341
    342
    343
    344
    345
    346
    347
    348
    349
    350
    351
    352
    353
    354
    355
    356
    357
    358
    359
    360
    361
    362
    363
    364
    365
    366
    367
    368
    369
    370
    371
    372
    373
    374
    375
    376
    377
    378
    379
    380
    381
    382
    383
    384
    385
    386
    387
    388
    389
    390
    391
    392
    393
    394
    395
    396
    397
    398
    399
    400
    401
    402
    403
    404
    405
    406
    407
    408
    409
    410
    411
    412
    413
    414
    415
    416
    417
    418
    419
    420
    421
    422
    423
    424
    425
    426
    427
    428
    429
    430
    431
    432
    433
    434
    435
    436
    437
    438
    439
    440
    441
    442
    443
    444
    445
    446
    447
    448
    449
    450
    451
    452
    453
    454
    455
    456
    457
    458
    459
    460
    461
    462
    463
    464
    465
    466
    467
    468
    469
    470

    // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
    // file at the top-level directory of this distribution and at
    // http://rust-lang.org/COPYRIGHT.
    //
    // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
    // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
    // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
    // option. This file may not be copied, modified, or distributed
    // except according to those terms.

    //! # The Rust Standard Library
    //!
    //! The Rust Standard Library is the foundation of portable Rust software, a
    //! set of minimal and battle-tested shared abstractions for the [broader Rust
    //! ecosystem][crates.io]. It offers core types, like [`Vec<T>`] and
    //! [`Option<T>`], library-defined [operations on language
    //! primitives](#primitives), [standard macros](#macros), [I/O] and
    //! [multithreading], among [many other things][other].
    //!
    //! `std` is available to all Rust crates by default, just as if each one
    //! contained an `extern crate std;` import at the [crate root]. Therefore the
    //! standard library can be accessed in [`use`] statements through the path
    //! `std`, as in [`use std::env`], or in expressions through the absolute path
    //! `::std`, as in [`::std::env::args()`].
    //!
    //! # How to read this documentation
    //!
    //! If you already know the name of what you are looking for, the fastest way to
    //! find it is to use the <a href="#" onclick="focusSearchBar();">search
    //! bar</a> at the top of the page.
    //!
    //! Otherwise, you may want to jump to one of these useful sections:
    //!
    //! * [`std::*` modules](#modules)
    //! * [Primitive types](#primitives)
    //! * [Standard macros](#macros)
    //! * [The Rust Prelude](prelude/index.html)
    //!
    //! If this is your first time, the documentation for the standard library is
    //! written to be casually perused. Clicking on interesting things should
    //! generally lead you to interesting places. Still, there are important bits
    //! you don't want to miss, so read on for a tour of the standard library and
    //! its documentation!
    //!
    //! Once you are familiar with the contents of the standard library you may
    //! begin to find the verbosity of the prose distracting. At this stage in your
    //! development you may want to press the **[-]** button near the top of the
    //! page to collapse it into a more skimmable view.
    //!
    //! While you are looking at that **[-]** button also notice the **[src]**
    //! button. Rust's API documentation comes with the source code and you are
    //! encouraged to read it. The standard library source is generally high
    //! quality and a peek behind the curtains is often enlightening.
    //!
    //! # What is in the standard library documentation?
    //!
    //! First of all, The Rust Standard Library is divided into a number of focused
    //! modules, [all listed further down this page](#modules). These modules are
    //! the bedrock upon which all of Rust is forged, and they have mighty names
    //! like [`std::slice`] and [`std::cmp`]. Modules' documentation typically
    //! includes an overview of the module along with examples, and are a smart
    //! place to start familiarizing yourself with the library.
    //!
    //! Second, implicit methods on [primitive types] are documented here. This can
    //! be a source of confusion for two reasons:
    //!
    //! 1. While primitives are implemented by the compiler, the standard library
    //!    implements methods directly on the primitive types (and it is the only
    //!    library that does so), which are [documented in the section on
    //!    primitives](#primitives).
    //! 2. The standard library exports many modules *with the same name as
    //!    primitive types*. These define additional items related to the primitive
    //!    type, but not the all-important methods.
    //!
    //! So for example there is a [page for the primitive type
    //! `i32`](primitive.i32.html) that lists all the methods that can be called on
    //! 32-bit integers (very useful), and there is a [page for the module
    //! `std::i32`](i32/index.html) that documents the constant values [`MIN`] and
    //! [`MAX`](i32/constant.MAX.html) (rarely useful).
    //!
    //! Note the documentation for the primitives [`str`] and [`[T]`][slice] (also
    //! called 'slice'). Many method calls on [`String`] and [`Vec<T>`] are actually
    //! calls to methods on [`str`] and [`[T]`][slice] respectively, via [deref
    //! coercions].
    //!
    //! Third, the standard library defines [The Rust Prelude], a small collection
    //! of items - mostly traits - that are imported into every module of every
    //! crate. The traits in the prelude are pervasive, making the prelude
    //! documentation a good entry point to learning about the library.
    //!
    //! And finally, the standard library exports a number of standard macros, and
    //! [lists them on this page](#macros) (technically, not all of the standard
    //! macros are defined by the standard library - some are defined by the
    //! compiler - but they are documented here the same). Like the prelude, the
    //! standard macros are imported by default into all crates.
    //!
    //! # A Tour of The Rust Standard Library
    //!
    //! The rest of this crate documentation is dedicated to pointing out notable
    //! features of The Rust Standard Library.
    //!
    //! ## Containers and collections
    //!
    //! The [`option`] and [`result`] modules define optional and error-handling
    //! types, [`Option<T>`] and [`Result<T, E>`]. The [`iter`] module defines
    //! Rust's iterator trait, [`Iterator`], which works with the [`for`] loop to
    //! access collections.
    //!
    //! The standard library exposes three common ways to deal with contiguous
    //! regions of memory:
    //!
    //! * [`Vec<T>`] - A heap-allocated *vector* that is resizable at runtime.
    //! * [`[T; n]`][array] - An inline *array* with a fixed size at compile time.
    //! * [`[T]`][slice] - A dynamically sized *slice* into any other kind of contiguous
    //!   storage, whether heap-allocated or not.
    //!
    //! Slices can only be handled through some kind of *pointer*, and as such come
    //! in many flavors such as:
    //!
    //! * `&[T]` - *shared slice*
    //! * `&mut [T]` - *mutable slice*
    //! * [`Box<[T]>`][owned slice] - *owned slice*
    //!
    //! [`str`], a UTF-8 string slice, is a primitive type, and the standard library
    //! defines many methods for it. Rust [`str`]s are typically accessed as
    //! immutable references: `&str`. Use the owned [`String`] for building and
    //! mutating strings.
    //!
    //! For converting to strings use the [`format!`] macro, and for converting from
    //! strings use the [`FromStr`] trait.
    //!
    //! Data may be shared by placing it in a reference-counted box or the [`Rc`]
    //! type, and if further contained in a [`Cell`] or [`RefCell`], may be mutated
    //! as well as shared. Likewise, in a concurrent setting it is common to pair an
    //! atomically-reference-counted box, [`Arc`], with a [`Mutex`] to get the same
    //! effect.
    //!
    //! The [`collections`] module defines maps, sets, linked lists and other
    //! typical collection types, including the common [`HashMap<K, V>`].
    //!
    //! ## Platform abstractions and I/O
    //!
    //! Besides basic data types, the standard library is largely concerned with
    //! abstracting over differences in common platforms, most notably Windows and
    //! Unix derivatives.
    //!
    //! Common types of I/O, including [files], [TCP], [UDP], are defined in the
    //! [`io`], [`fs`], and [`net`] modules.
    //!
    //! The [`thread`] module contains Rust's threading abstractions. [`sync`]
    //! contains further primitive shared memory types, including [`atomic`] and
    //! [`mpsc`], which contains the channel types for message passing.
    //!
    //! [I/O]: io/index.html
    //! [`MIN`]: i32/constant.MIN.html
    //! [TCP]: net/struct.TcpStream.html
    //! [The Rust Prelude]: prelude/index.html
    //! [UDP]: net/struct.UdpSocket.html
    //! [`::std::env::args()`]: env/fn.args.html
    //! [`Arc`]: sync/struct.Arc.html
    //! [owned slice]: boxed/index.html
    //! [`Cell`]: cell/struct.Cell.html
    //! [`FromStr`]: str/trait.FromStr.html
    //! [`HashMap<K, V>`]: collections/struct.HashMap.html
    //! [`Iterator`]: iter/trait.Iterator.html
    //! [`Mutex`]: sync/struct.Mutex.html
    //! [`Option<T>`]: option/enum.Option.html
    //! [`Rc`]: rc/index.html
    //! [`RefCell`]: cell/struct.RefCell.html
    //! [`Result<T, E>`]: result/enum.Result.html
    //! [`String`]: string/struct.String.html
    //! [`Vec<T>`]: vec/index.html
    //! [array]: primitive.array.html
    //! [slice]: primitive.slice.html
    //! [`atomic`]: sync/atomic/index.html
    //! [`collections`]: collections/index.html
    //! [`for`]: ../book/loops.html#for
    //! [`format!`]: macro.format!.html
    //! [`fs`]: fs/index.html
    //! [`io`]: io/index.html
    //! [`iter`]: iter/index.html
    //! [`mpsc`]: sync/mpsc/index.html
    //! [`net`]: net/index.html
    //! [`option`]: option/index.html
    //! [`result`]: result/index.html
    //! [`std::cmp`]: cmp/index.html
    //! [`std::slice`]: slice/index.html
    //! [`str`]: primitive.str.html
    //! [`sync`]: sync/index.html
    //! [`thread`]: thread/index.html
    //! [`use std::env`]: env/index.html
    //! [`use`]: ../book/crates-and-modules.html#importing-modules-with-use
    //! [crate root]: ../book/crates-and-modules.html#basic-terminology-crates-and-modules
    //! [crates.io]: https://crates.io
    //! [deref coercions]: ../book/deref-coercions.html
    //! [files]: fs/struct.File.html
    //! [multithreading]: thread/index.html
    //! [other]: #what-is-in-the-standard-library-documentation
    //! [primitive types]: ../book/primitive-types.html

    #![crate_name = "std"]
    #![stable(feature = "rust1", since = "1.0.0")]
    #![crate_type = "rlib"]
    #![crate_type = "dylib"]
    #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
           html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
           html_root_url = "https://doc.rust-lang.org/nightly/",
           html_playground_url = "https://play.rust-lang.org/",
           issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
           test(no_crate_inject, attr(deny(warnings))),
           test(attr(allow(dead_code, deprecated, unused_variables, unused_mut))))]

    #![needs_panic_runtime]

    #![feature(alloc)]
    #![feature(allow_internal_unstable)]
    #![feature(asm)]
    #![feature(associated_consts)]
    #![feature(borrow_state)]
    #![feature(box_syntax)]
    #![feature(cfg_target_vendor)]
    #![feature(cfg_target_thread_local)]
    #![feature(char_internals)]
    #![feature(collections)]
    #![feature(collections_bound)]
    #![feature(const_fn)]
    #![feature(core_float)]
    #![feature(core_intrinsics)]
    #![feature(dropck_parametricity)]
    #![feature(float_extras)]
    #![feature(float_from_str_radix)]
    #![feature(fnbox)]
    #![feature(fn_traits)]
    #![feature(heap_api)]
    #![feature(hashmap_hasher)]
    #![feature(inclusive_range)]
    #![feature(int_error_internals)]
    #![feature(into_cow)]
    #![feature(lang_items)]
    #![feature(libc)]
    #![feature(link_args)]
    #![feature(linkage)]
    #![feature(macro_reexport)]
    #![cfg_attr(test, feature(map_values_mut))]
    #![feature(num_bits_bytes)]
    #![feature(old_wrapping)]
    #![feature(on_unimplemented)]
    #![feature(oom)]
    #![feature(optin_builtin_traits)]
    #![feature(panic_unwind)]
    #![feature(placement_in_syntax)]
    #![feature(rand)]
    #![feature(raw)]
    #![feature(repr_simd)]
    #![feature(reflect_marker)]
    #![feature(rustc_attrs)]
    #![feature(shared)]
    #![feature(sip_hash_13)]
    #![feature(slice_bytes)]
    #![feature(slice_concat_ext)]
    #![feature(slice_patterns)]
    #![feature(staged_api)]
    #![feature(stmt_expr_attributes)]
    #![feature(str_char)]
    #![feature(str_internals)]
    #![feature(str_utf16)]
    #![feature(test, rustc_private)]
    #![feature(thread_local)]
    #![feature(unboxed_closures)]
    #![feature(unicode)]
    #![feature(unique)]
    #![feature(unsafe_no_drop_flag, filling_drop)]
    #![feature(unwind_attributes)]
    #![feature(vec_push_all)]
    #![feature(zero_one)]
    #![feature(question_mark)]
    #![feature(try_from)]
    #![feature(needs_panic_runtime)]

    // Issue# 30592: Systematically use alloc_system during stage0 since jemalloc
    // might be unavailable or disabled
    #![cfg_attr(stage0, feature(alloc_system))]

    // Don't link to std. We are std.
    #![no_std]

    #![deny(missing_docs)]
    #![allow(unused_features)] // std may use features in a platform-specific way
    #![cfg_attr(not(stage0), deny(warnings))]

    #[cfg(test)] extern crate test;

    // We want to reexport a few macros from core but libcore has already been
    // imported by the compiler (via our #[no_std] attribute) In this case we just
    // add a new crate name so we can attach the reexports to it.
    #[macro_reexport(assert, assert_eq, debug_assert, debug_assert_eq,
                     unreachable, unimplemented, write, writeln, try)]
    extern crate core as __core;

    #[macro_use]
    #[macro_reexport(vec, format)]
    extern crate collections as core_collections;

    #[allow(deprecated)] extern crate rand as core_rand;
    extern crate alloc;
    extern crate rustc_unicode;
    extern crate libc;

    // We always need an unwinder currently for backtraces
    extern crate unwind;

    #[cfg(stage0)]
    extern crate alloc_system;

    // Make std testable by not duplicating lang items and other globals. See #2912
    #[cfg(test)] extern crate std as realstd;

    // NB: These reexports are in the order they should be listed in rustdoc

    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::any;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::cell;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::clone;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::cmp;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::convert;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::default;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::hash;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::intrinsics;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::iter;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::marker;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::mem;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::ops;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::ptr;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::raw;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::result;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::option;

    pub mod error;

    #[stable(feature = "rust1", since = "1.0.0")]
    pub use alloc::boxed;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use alloc::rc;

    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core_collections::borrow;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core_collections::fmt;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core_collections::slice;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core_collections::str;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core_collections::string;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core_collections::vec;

    #[stable(feature = "rust1", since = "1.0.0")]
    pub use rustc_unicode::char;

    /* Exported macros */

    #[macro_use]
    mod macros;

    mod rtdeps;

    /* The Prelude. */

    pub mod prelude;

    /* Primitive types */

    // NB: slice and str are primitive types too, but their module docs + primitive
    // doc pages are inlined from the public re-exports of core_collections::{slice,
    // str} above.

    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::isize;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::i8;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::i16;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::i32;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::i64;

    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::usize;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::u8;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::u16;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::u32;
    #[stable(feature = "rust1", since = "1.0.0")]
    pub use core::u64;

    #[path = "num/f32.rs"]   pub mod f32;
    #[path = "num/f64.rs"]   pub mod f64;

    pub mod ascii;

    /* Common traits */

    pub mod num;

    /* Runtime and platform support */

    #[macro_use]
    pub mod thread;

    pub mod collections;
    pub mod env;
    pub mod ffi;
    pub mod fs;
    pub mod io;
    pub mod net;
    pub mod os;
    pub mod panic;
    pub mod path;
    pub mod process;
    pub mod sync;
    pub mod time;
    mod memchr;

    #[macro_use]
    #[path = "sys/common/mod.rs"] mod sys_common;

    #[cfg(unix)]
    #[path = "sys/unix/mod.rs"] mod sys;
    #[cfg(windows)]
    #[path = "sys/windows/mod.rs"] mod sys;

    pub mod rt;
    mod panicking;
    mod rand;

    // Some external utilities of the standard library rely on randomness (aka
    // rustc_back::TempDir and tests) and need a way to get at the OS rng we've got
    // here. This module is not at all intended for stabilization as-is, however,
    // but it may be stabilized long-term. As a result we're exposing a hidden,
    // unstable module so we can get our build working.
    #[doc(hidden)]
    #[unstable(feature = "rand", issue = "0")]
    pub mod __rand {
        pub use rand::{thread_rng, ThreadRng, Rng};
    }

    // Include a number of private modules that exist solely to provide
    // the rustdoc documentation for primitive types. Using `include!`
    // because rustdoc only looks for these modules at the crate level.
    include!("primitive_docs.rs");

# Help

## Keyboard Shortcuts

?
  Show this help dialog
S
  Focus the search field
⇤
  Move up in search results
⇥
  Move down in search results
⏎
  Go to active search result
+
  Collapse/expand all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g. `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g. `vec -> usize` or `* -> vec`)