# Crate core [−] [src]

*Unstable*

# The Rust Core Library

The Rust Core Library is the dependency-free foundation of The Rust Standard Library. It is the portable glue between the language and its libraries, defining the intrinsic and primitive building blocks of all Rust code. It links to no upstream libraries, no system libraries, and no libc.

The core library is *minimal*: it isn't even aware of heap allocation,
nor does it provide concurrency or I/O. These things require
platform integration, and this library is platform-agnostic.

*It is not recommended to use the core library*. The stable
functionality of libcore is reexported from the
standard library. The composition of this library is
subject to change over time; only the interface exposed through libstd is
intended to be stable.

# How to use the core library

This library is built on the assumption of a few existing symbols:

`memcpy`

,`memcmp`

,`memset`

- These are core memory routines which are often generated by LLVM. Additionally, this library can make explicit calls to these functions. Their signatures are the same as found in C. These functions are often provided by the system libc, but can also be provided by the rlibc crate.`rust_begin_unwind`

- This function takes three arguments, a`fmt::Arguments`

, a`&str`

, and a`u32`

. These three arguments dictate the panic message, the file at which panic was invoked, and the line. It is up to consumers of this core library to define this panic function; it is only required to never return.

## Primitive Types

array |
Implementations of things like |

bool | |

char |
Character manipulation. |

f32 |
Operations and constants for 32-bits floats ( |

f64 |
Operations and constants for 64-bits floats ( |

i16 |
Operations and constants for signed 16-bits integers ( |

i32 |
Operations and constants for signed 32-bits integers ( |

i64 |
Operations and constants for signed 64-bits integers ( |

i8 |
Operations and constants for signed 8-bits integers ( |

isize |
Operations and constants for pointer-sized signed integers ( |

pointer |
Operations on unsafe pointers, |

slice |
Slice management and manipulation |

str |
String manipulation |

tuple |
Operations on tuples |

u16 |
Operations and constants for unsigned 16-bits integers ( |

u32 |
Operations and constants for unsigned 32-bits integers ( |

u64 |
Operations and constants for unsigned 64-bits integer ( |

u8 |
Operations and constants for unsigned 8-bits integers ( |

usize |
Operations and constants for pointer-sized unsigned integers ( |

## Modules

any |
Traits for dynamic typing of any |

atomic |
Atomic types |

cell |
Shareable mutable containers. |

clone |
The |

cmp |
Functionality for ordering and comparison. |

convert |
Traits for conversions between types. |

default |
The |

f32 |
Operations and constants for 32-bits floats ( |

f64 |
Operations and constants for 64-bits floats ( |

fmt |
Utilities for formatting and printing strings |

hash |
Generic hashing support. |

i16 |
Operations and constants for signed 16-bits integers ( |

i32 |
Operations and constants for signed 32-bits integers ( |

i64 |
Operations and constants for signed 64-bits integers ( |

i8 |
Operations and constants for signed 8-bits integers ( |

isize |
Operations and constants for pointer-sized signed integers ( |

iter |
Composable external iterators |

marker |
Primitive traits and marker types representing basic 'kinds' of types. |

mem |
Basic functions for dealing with memory |

num |
Numeric traits and functions for the built-in numeric types. |

ops |
Overloadable operators |

option |
Optional values |

ptr |
Operations on unsafe pointers, |

result |
Error handling with the |

slice |
Slice management and manipulation |

u16 |
Operations and constants for unsigned 16-bits integers ( |

u32 |
Operations and constants for unsigned 32-bits integers ( |

u64 |
Operations and constants for unsigned 64-bits integer ( |

u8 |
Operations and constants for unsigned 8-bits integers ( |

usize |
Operations and constants for pointer-sized unsigned integers ( |

array |
[Unstable] Implementations of things like |

char |
[Unstable] Character manipulation. |

intrinsics |
[Unstable] rustc compiler intrinsics. |

nonzero |
[Unstable] Exposes the NonZero lang item which provides optimization hints. |

panicking |
[Unstable] Panic support for libcore |

prelude |
[Unstable] The core prelude |

raw |
[Unstable] Contains struct definitions for the layout of compiler built-in types. |

simd |
[Unstable] SIMD vectors. |

str |
[Unstable] String manipulation |

## Macros

__impl_slice_eq1! | |

__impl_slice_eq2! | |

assert! |
Ensure that a boolean expression is |

assert_eq! |
Asserts that two expressions are equal to each other. |

debug_assert! |
Ensure that a boolean expression is |

debug_assert_eq! |
Asserts that two expressions are equal to each other, testing equality in both directions. |

panic! |
Entry point of thread panic, for details, see std::macros |

try! |
Short circuiting evaluation on Err |

unimplemented! |
A standardised placeholder for marking unfinished code. It panics with the
message |

unreachable! |
A utility macro for indicating unreachable code. |

write! |
Use the |

writeln! |
Equivalent to the |