Search for the first occurrence of a byte in a slice.
This returns the index corresponding to the first occurrence of
None if one is not found.
While this is operationally the same as something like
haystack.iter().position(|&b| b == needle),
memchr will use a highly
optimized routine that can be up to an order of magnitude faster in some
This shows how to find the first position of a byte in a byte string.
use memchr::memchr; let haystack = b"the quick brown fox"; assert_eq!(memchr(b'k', haystack), Some(8));