Struct FromUtf8Error

pub struct FromUtf8Error { /* private fields */ }

A possible error value when converting a String from a UTF-8 byte vector.

This type is the error type for the from_utf8 method on String. It is designed in such a way to carefully avoid reallocations: the into_bytes method will give back the byte vector that was used in the conversion attempt.

The Utf8Error type provided by std::str represents an error that may occur when converting a slice of u8s to a &str. In this sense, it’s an analogue to FromUtf8Error, and you can get one from a FromUtf8Error through the utf8_error method.

Examples

// some invalid bytes, in a vector
let bytes = vec![0, 159];

let value = String::from_utf8(bytes);

assert!(value.is_err());
assert_eq!(vec![0, 159], value.unwrap_err().into_bytes());

Implementations

impl FromUtf8Error

pub fn as_bytes(&self) -> &[u8]

Returns a slice of u8s bytes that were attempted to convert to a String.

Examples

// some invalid bytes, in a vector
let bytes = vec![0, 159];

let value = String::from_utf8(bytes);

assert_eq!(&[0, 159], value.unwrap_err().as_bytes());

pub fn into_utf8_lossy(self) -> String

🔬This is a nightly-only experimental API. (string_from_utf8_lossy_owned)

Available on non-no_global_oom_handling only.

Converts the bytes into a String lossily, substituting invalid UTF-8 sequences with replacement characters.

See String::from_utf8_lossy for more details on replacement of invalid sequences, and String::from_utf8_lossy_owned for the String function which corresponds to this function.

Examples

#![feature(string_from_utf8_lossy_owned)]
// some invalid bytes
let input: Vec<u8> = b"Hello \xF0\x90\x80World".into();
let output = String::from_utf8(input).unwrap_or_else(|e| e.into_utf8_lossy());

assert_eq!(String::from("Hello �World"), output);

pub fn into_bytes(self) -> Vec<u8>

Returns the bytes that were attempted to convert to a String.

This method is carefully constructed to avoid allocation. It will consume the error, moving out the bytes, so that a copy of the bytes does not need to be made.

Examples

// some invalid bytes, in a vector
let bytes = vec![0, 159];

let value = String::from_utf8(bytes);

assert_eq!(vec![0, 159], value.unwrap_err().into_bytes());

pub fn utf8_error(&self) -> Utf8Error

Fetch a Utf8Error to get more details about the conversion failure.

The Utf8Error type provided by std::str represents an error that may occur when converting a slice of u8s to a &str. In this sense, it’s an analogue to FromUtf8Error. See its documentation for more details on using it.

Examples

// some invalid bytes, in a vector
let bytes = vec![0, 159];

let error = String::from_utf8(bytes).unwrap_err().utf8_error();

// the first byte is invalid here
assert_eq!(1, error.valid_up_to());

Trait Implementations

impl Clone for FromUtf8Error

fn clone(&self) -> FromUtf8Error

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FromUtf8Error

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Display for FromUtf8Error

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Error for FromUtf8Error

fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl PartialEq for FromUtf8Error

fn eq(&self, other: &FromUtf8Error) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for FromUtf8Error

impl StructuralPartialEq for FromUtf8Error

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 40 bytes