pub const fn from_utf8(v: &[u8]) -> Result<&str, Utf8Error>Expand description
Converts a slice of bytes to a string slice.
A string slice (&str) is made of bytes (u8), and a byte slice
(&[u8]) is made of bytes, so this function converts between
the two. Not all byte slices are valid string slices, however: &str requires
that it is valid UTF-8. from_utf8() checks to ensure that the bytes are valid
UTF-8, and then does the conversion.
If you are sure that the byte slice is valid UTF-8, and you don’t want to
incur the overhead of the validity check, there is an unsafe version of
this function, from_utf8_unchecked, which has the same
behavior but skips the check.
If you need a String instead of a &str, consider
String::from_utf8.
Because you can stack-allocate a [u8; N], and you can take a
&[u8] of it, this function is one way to have a
stack-allocated string. There is an example of this in the
examples section below.
Errors
Returns Err if the slice is not UTF-8 with a description as to why the
provided slice is not UTF-8.
Examples
Basic usage:
use std::str;
// some bytes, in a vector
let sparkle_heart = vec![240, 159, 146, 150];
// We know these bytes are valid, so just use `unwrap()`.
let sparkle_heart = str::from_utf8(&sparkle_heart).unwrap();
assert_eq!("💖", sparkle_heart);Incorrect bytes:
use std::str;
// some invalid bytes, in a vector
let sparkle_heart = vec![0, 159, 146, 150];
assert!(str::from_utf8(&sparkle_heart).is_err());See the docs for Utf8Error for more details on the kinds of
errors that can be returned.
A “stack allocated string”:
use std::str;
// some bytes, in a stack-allocated array
let sparkle_heart = [240, 159, 146, 150];
// We know these bytes are valid, so just use `unwrap()`.
let sparkle_heart: &str = str::from_utf8(&sparkle_heart).unwrap();
assert_eq!("💖", sparkle_heart);