FromUtf8Error in alloc::string - Rust
Description: A possible error value when converting a `String` from a UTF-8 byte vector.
Keywords: rust, rustlang, rust-lang, FromUtf8Error

# Struct alloc::string::FromUtf8Error
1.0.0[−][src]

    pub struct FromUtf8Error { /* fields omitted */ }

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 `u8`s 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[src]

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

Returns a slice of `u8`s 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());

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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 `u8`s 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 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 `==`. Read more

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

This method tests for `!=`.

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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

### impl RefUnwindSafe for FromUtf8Error

### impl Send for FromUtf8Error

### impl Sync for FromUtf8Error

### impl Unpin for FromUtf8Error

### impl UnwindSafe for FromUtf8Error

## Blanket Implementations

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

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#### pub fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more

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### impl<T> Borrow<T> for T where
T: ?Sized,

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#### pub fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

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### impl<T> BorrowMut<T> for T where
T: ?Sized,

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#### pub 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

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#### pub fn from(t: T) -> T

Performs the conversion.

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### impl<T, U> Into<U> for T where
U: From<T>,

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#### pub fn into(self) -> U

Performs the conversion.

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### impl<T> ToOwned for T where
T: Clone,

#### type Owned = T

The resulting type after obtaining ownership.

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#### pub fn to_owned(&Self) -> T

Creates owned data from borrowed data, usually by cloning. Read more

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#### pub fn clone_into(&Self, &mut T)

🔬 This is a nightly-only experimental API. (`toowned_clone_into` #41263)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

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### impl<T> ToString for T where
T: Display + ?Sized,

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#### pub 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 T where
U: Into<T>,

#### type Error = Infallible

The type returned in the event of a conversion error.

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#### pub 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 T where
U: TryFrom<T>,

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

The type returned in the event of a conversion error.

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

Performs the conversion.