# Crate memchr [−] [src]

The `memchr` crate provides heavily optimized routines for searching bytes.

The `memchr` function is traditionally provided by libc, however, the performance of `memchr` can vary significantly depending on the specific implementation of libc that is used. They can range from manually tuned Assembly implementations (like that found in GNU’s libc) all the way to non-vectorized C implementations (like that found in MUSL).

To smooth out the differences between implementations of libc, at least on `x86_64` for Rust 1.27+, this crate provides its own implementation of `memchr` that should perform competitively with the one found in GNU’s libc. The implementation is in pure Rust and has no dependency on a C compiler or an Assembler.

Additionally, GNU libc also provides an extension, `memrchr`. This crate provides its own implementation of `memrchr` as well, on top of `memchr2`, `memchr3`, `memrchr2` and `memrchr3`. The difference between `memchr` and `memchr2` is that that `memchr2` permits finding all occurrences of two bytes instead of one. Similarly for `memchr3`.

## Structs

Memchr | An iterator for `memchr`.
Memchr2 | An iterator for `memchr2`.
Memchr3 | An iterator for `memchr3`.

## Functions

memchr | Search for the first occurrence of a byte in a slice.
memchr2 | Like `memchr`, but searches for either of two bytes instead of just one.
memchr2_iter | An iterator over all occurrences of the needles in a haystack.
memchr3 | Like `memchr`, but searches for any of three bytes instead of just one.
memchr3_iter | An iterator over all occurrences of the needles in a haystack.
memchr_iter | An iterator over all occurrences of the needle in a haystack.
memrchr | Search for the last occurrence of a byte in a slice.
memrchr2 | Like `memrchr`, but searches for either of two bytes instead of just one.
memrchr2_iter | An iterator over all occurrences of the needles in a haystack, in reverse.
memrchr3 | Like `memrchr`, but searches for any of three bytes instead of just one.
memrchr3_iter | An iterator over all occurrences of the needles in a haystack, in reverse.
memrchr_iter | An iterator over all occurrences of the needle in a haystack, in reverse.