Struct alloc::string::FromUtf8Error

1.0.0 · source ·
pub struct FromUtf8Error { /* private fields */ }
Expand description

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

Basic usage:

// 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());
Run

Implementations§

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impl FromUtf8Error

1.26.0 · source

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

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

Examples

Basic usage:

// 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());
Run
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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

Basic usage:

// 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());
Run
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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

Basic usage:

// 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());
Run

Trait Implementations§

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impl Clone for FromUtf8Error

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fn clone(&self) -> FromUtf8Error

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for FromUtf8Error

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

Formats the value using the given formatter. Read more
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impl Display for FromUtf8Error

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

Formats the value using the given formatter. Read more
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impl Error for FromUtf8Error

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fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()
1.30.0 · source§

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

The lower-level source of this error, if any. Read more
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fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting
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fn provide<'a>(&'a self, demand: &mut Demand<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access #99301)
Provides type based access to context intended for error reports. Read more
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impl PartialEq<FromUtf8Error> for FromUtf8Error

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

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl Eq for FromUtf8Error

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impl StructuralEq for FromUtf8Error

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impl StructuralPartialEq for FromUtf8Error

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for Twhere
    T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere
    T: ?Sized,

const: unstable · source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere
    T: ?Sized,

const: unstable · source§

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere
    U: From<T>,

const: unstable · source§

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<E> Provider for Ewhere
    E: Error + ?Sized,

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fn provide<'a>(&'a self, demand: &mut Demand<'a>)

🔬This is a nightly-only experimental API. (provide_any #96024)
Data providers should implement this method to provide all values they are able to provide by using demand. Read more
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impl<T> ToOwned for Twhere
    T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T> ToString for Twhere
    T: Display + ?Sized,

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default fn to_string(&self) -> String

Converts the given value to a String. Read more
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impl<T, U> TryFrom<U> for Twhere
    U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
const: unstable · source§

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere
    U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
const: unstable · source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.