# Trait num_traits::cast::FromPrimitive [−] [src]

    pub trait FromPrimitive: Sized {
        fn from_i64(n: i64) -> Option<Self>;
        fn from_u64(n: u64) -> Option<Self>;

        fn from_isize(n: isize) -> Option<Self> { ... }
        fn from_i8(n: i8) -> Option<Self> { ... }
        fn from_i16(n: i16) -> Option<Self> { ... }
        fn from_i32(n: i32) -> Option<Self> { ... }
        fn from_i128(n: i128) -> Option<Self> { ... }
        fn from_usize(n: usize) -> Option<Self> { ... }
        fn from_u8(n: u8) -> Option<Self> { ... }
        fn from_u16(n: u16) -> Option<Self> { ... }
        fn from_u32(n: u32) -> Option<Self> { ... }
        fn from_u128(n: u128) -> Option<Self> { ... }
        fn from_f32(n: f32) -> Option<Self> { ... }
        fn from_f64(n: f64) -> Option<Self> { ... }
    }

A generic trait for converting a number to a value.

A value can be represented by the target type when it lies within the range of scalars supported by the target type. For example, a negative integer cannot be represented by an unsigned integer type, and an `i64` with a very high magnitude might not be convertible to an `i32`. On the other hand, conversions with possible precision loss or truncation are admitted, like an `f32` with a decimal part to an integer type, or even a large `f64` saturating to `f32` infinity.

## Required methods

### `fn from_i64(n: i64) -> Option<Self>` [src]

Converts an `i64` to return an optional value of this type. If the value cannot be represented by this type, then `None` is returned.

### `fn from_u64(n: u64) -> Option<Self>` [src]

Converts an `u64` to return an optional value of this type. If the value cannot be represented by this type, then `None` is returned.

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## Provided methods

### `fn from_isize(n: isize) -> Option<Self>` [src]

Converts an `isize` to return an optional value of this type. If the value cannot be represented by this type, then `None` is returned.

### `fn from_i8(n: i8) -> Option<Self>` [src]

Converts an `i8` to return an optional value of this type. If the value cannot be represented by this type, then `None` is returned.

### `fn from_i16(n: i16) -> Option<Self>` [src]

Converts an `i16` to return an optional value of this type. If the value cannot be represented by this type, then `None` is returned.

### `fn from_i32(n: i32) -> Option<Self>` [src]

Converts an `i32` to return an optional value of this type. If the value cannot be represented by this type, then `None` is returned.

### `fn from_i128(n: i128) -> Option<Self>` [src]

Converts an `i128` to return an optional value of this type. If the value cannot be represented by this type, then `None` is returned.

This method is only available with feature `i128` enabled on Rust >= 1.26.

The default implementation converts through `from_i64()`. Types implementing this trait should override this method if they can represent a greater range.

### `fn from_usize(n: usize) -> Option<Self>` [src]

Converts a `usize` to return an optional value of this type. If the value cannot be represented by this type, then `None` is returned.

### `fn from_u8(n: u8) -> Option<Self>` [src]

Converts an `u8` to return an optional value of this type. If the value cannot be represented by this type, then `None` is returned.

### `fn from_u16(n: u16) -> Option<Self>` [src]

Converts an `u16` to return an optional value of this type. If the value cannot be represented by this type, then `None` is returned.

### `fn from_u32(n: u32) -> Option<Self>` [src]

Converts an `u32` to return an optional value of this type. If the value cannot be represented by this type, then `None` is returned.

### `fn from_u128(n: u128) -> Option<Self>` [src]

Converts an `u128` to return an optional value of this type. If the value cannot be represented by this type, then `None` is returned.

This method is only available with feature `i128` enabled on Rust >= 1.26.

The default implementation converts through `from_u64()`. Types implementing this trait should override this method if they can represent a greater range.

### `fn from_f32(n: f32) -> Option<Self>` [src]

Converts a `f32` to return an optional value of this type. If the value cannot be represented by this type, then `None` is returned.

### `fn from_f64(n: f64) -> Option<Self>` [src]

Converts a `f64` to return an optional value of this type. If the value cannot be represented by this type, then `None` is returned.

The default implementation tries to convert through `from_i64()`, and failing that through `from_u64()`. Types implementing this trait should override this method if they can represent a greater range.

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## Implementations on Foreign Types

### `impl<T: FromPrimitive> FromPrimitive for Wrapping<T>` [src]

#### `fn from_isize(n: isize) -> Option<Self>` [src]

#### `fn from_i8(n: i8) -> Option<Self>` [src]

#### `fn from_i16(n: i16) -> Option<Self>` [src]

#### `fn from_i32(n: i32) -> Option<Self>` [src]

#### `fn from_i64(n: i64) -> Option<Self>` [src]

#### `fn from_i128(n: i128) -> Option<Self>` [src]

#### `fn from_usize(n: usize) -> Option<Self>` [src]

#### `fn from_u8(n: u8) -> Option<Self>` [src]

#### `fn from_u16(n: u16) -> Option<Self>` [src]

#### `fn from_u32(n: u32) -> Option<Self>` [src]

#### `fn from_u64(n: u64) -> Option<Self>` [src]

#### `fn from_u128(n: u128) -> Option<Self>` [src]

#### `fn from_f32(n: f32) -> Option<Self>` [src]

#### `fn from_f64(n: f64) -> Option<Self>` [src]

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## Implementors

### `impl FromPrimitive for f32` [src]

#### `fn from_isize(n: isize) -> Option<f32>` [src]

#### `fn from_i8(n: i8) -> Option<f32>` [src]

#### `fn from_i16(n: i16) -> Option<f32>` [src]

#### `fn from_i32(n: i32) -> Option<f32>` [src]

#### `fn from_i64(n: i64) -> Option<f32>` [src]

#### `fn from_i128(n: i128) -> Option<f32>` [src]

#### `fn from_usize(n: usize) -> Option<f32>` [src]

#### `fn from_u8(n: u8) -> Option<f32>` [src]

#### `fn from_u16(n: u16) -> Option<f32>` [src]

#### `fn from_u32(n: u32) -> Option<f32>` [src]

#### `fn from_u64(n: u64) -> Option<f32>` [src]

#### `fn from_u128(n: u128) -> Option<f32>` [src]

#### `fn from_f32(n: f32) -> Option<f32>` [src]

#### `fn from_f64(n: f64) -> Option<f32>` [src]

### `impl FromPrimitive for f64` [src]

#### `fn from_isize(n: isize) -> Option<f64>` [src]

#### `fn from_i8(n: i8) -> Option<f64>` [src]

#### `fn from_i16(n: i16) -> Option<f64>` [src]

#### `fn from_i32(n: i32) -> Option<f64>` [src]

#### `fn from_i64(n: i64) -> Option<f64>` [src]

#### `fn from_i128(n: i128) -> Option<f64>` [src]

#### `fn from_usize(n: usize) -> Option<f64>` [src]

#### `fn from_u8(n: u8) -> Option<f64>` [src]

#### `fn from_u16(n: u16) -> Option<f64>` [src]

#### `fn from_u32(n: u32) -> Option<f64>` [src]

#### `fn from_u64(n: u64) -> Option<f64>` [src]

#### `fn from_u128(n: u128) -> Option<f64>` [src]

#### `fn from_f32(n: f32) -> Option<f64>` [src]

#### `fn from_f64(n: f64) -> Option<f64>` [src]

### `impl FromPrimitive for i8` [src]

#### `fn from_isize(n: isize) -> Option<i8>` [src]

#### `fn from_i8(n: i8) -> Option<i8>` [src]

#### `fn from_i16(n: i16) -> Option<i8>` [src]

#### `fn from_i32(n: i32) -> Option<i8>` [src]

#### `fn from_i64(n: i64) -> Option<i8>` [src]

#### `fn from_i128(n: i128) -> Option<i8>` [src]

#### `fn from_usize(n: usize) -> Option<i8>` [src]

#### `fn from_u8(n: u8) -> Option<i8>` [src]

#### `fn from_u16(n: u16) -> Option<i8>` [src]

#### `fn from_u32(n: u32) -> Option<i8>` [src]

#### `fn from_u64(n: u64) -> Option<i8>` [src]

#### `fn from_u128(n: u128) -> Option<i8>` [src]

#### `fn from_f32(n: f32) -> Option<i8>` [src]

#### `fn from_f64(n: f64) -> Option<i8>` [src]

### `impl FromPrimitive for i16` [src]

#### `fn from_isize(n: isize) -> Option<i16>` [src]

#### `fn from_i8(n: i8) -> Option<i16>` [src]

#### `fn from_i16(n: i16) -> Option<i16>` [src]

#### `fn from_i32(n: i32) -> Option<i16>` [src]

#### `fn from_i64(n: i64) -> Option<i16>` [src]

#### `fn from_i128(n: i128) -> Option<i16>` [src]

#### `fn from_usize(n: usize) -> Option<i16>` [src]

#### `fn from_u8(n: u8) -> Option<i16>` [src]

#### `fn from_u16(n: u16) -> Option<i16>` [src]

#### `fn from_u32(n: u32) -> Option<i16>` [src]

#### `fn from_u64(n: u64) -> Option<i16>` [src]

#### `fn from_u128(n: u128) -> Option<i16>` [src]

#### `fn from_f32(n: f32) -> Option<i16>` [src]

#### `fn from_f64(n: f64) -> Option<i16>` [src]

### `impl FromPrimitive for i32` [src]

#### `fn from_isize(n: isize) -> Option<i32>` [src]

#### `fn from_i8(n: i8) -> Option<i32>` [src]

#### `fn from_i16(n: i16) -> Option<i32>` [src]

#### `fn from_i32(n: i32) -> Option<i32>` [src]

#### `fn from_i64(n: i64) -> Option<i32>` [src]

#### `fn from_i128(n: i128) -> Option<i32>` [src]

#### `fn from_usize(n: usize) -> Option<i32>` [src]

#### `fn from_u8(n: u8) -> Option<i32>` [src]

#### `fn from_u16(n: u16) -> Option<i32>` [src]

#### `fn from_u32(n: u32) -> Option<i32>` [src]

#### `fn from_u64(n: u64) -> Option<i32>` [src]

#### `fn from_u128(n: u128) -> Option<i32>` [src]

#### `fn from_f32(n: f32) -> Option<i32>` [src]

#### `fn from_f64(n: f64) -> Option<i32>` [src]

### `impl FromPrimitive for i64` [src]

#### `fn from_isize(n: isize) -> Option<i64>` [src]

#### `fn from_i8(n: i8) -> Option<i64>` [src]

#### `fn from_i16(n: i16) -> Option<i64>` [src]

#### `fn from_i32(n: i32) -> Option<i64>` [src]

#### `fn from_i64(n: i64) -> Option<i64>` [src]

#### `fn from_i128(n: i128) -> Option<i64>` [src]

#### `fn from_usize(n: usize) -> Option<i64>` [src]

#### `fn from_u8(n: u8) -> Option<i64>` [src]

#### `fn from_u16(n: u16) -> Option<i64>` [src]

#### `fn from_u32(n: u32) -> Option<i64>` [src]

#### `fn from_u64(n: u64) -> Option<i64>` [src]

#### `fn from_u128(n: u128) -> Option<i64>` [src]

#### `fn from_f32(n: f32) -> Option<i64>` [src]

#### `fn from_f64(n: f64) -> Option<i64>` [src]

### `impl FromPrimitive for i128` [src]

#### `fn from_isize(n: isize) -> Option<i128>` [src]

#### `fn from_i8(n: i8) -> Option<i128>` [src]

#### `fn from_i16(n: i16) -> Option<i128>` [src]

#### `fn from_i32(n: i32) -> Option<i128>` [src]

#### `fn from_i64(n: i64) -> Option<i128>` [src]

#### `fn from_i128(n: i128) -> Option<i128>` [src]

#### `fn from_usize(n: usize) -> Option<i128>` [src]

#### `fn from_u8(n: u8) -> Option<i128>` [src]

#### `fn from_u16(n: u16) -> Option<i128>` [src]

#### `fn from_u32(n: u32) -> Option<i128>` [src]

#### `fn from_u64(n: u64) -> Option<i128>` [src]

#### `fn from_u128(n: u128) -> Option<i128>` [src]

#### `fn from_f32(n: f32) -> Option<i128>` [src]

#### `fn from_f64(n: f64) -> Option<i128>` [src]

### `impl FromPrimitive for isize` [src]

#### `fn from_isize(n: isize) -> Option<isize>` [src]

#### `fn from_i8(n: i8) -> Option<isize>` [src]

#### `fn from_i16(n: i16) -> Option<isize>` [src]

#### `fn from_i32(n: i32) -> Option<isize>` [src]

#### `fn from_i64(n: i64) -> Option<isize>` [src]

#### `fn from_i128(n: i128) -> Option<isize>` [src]

#### `fn from_usize(n: usize) -> Option<isize>` [src]

#### `fn from_u8(n: u8) -> Option<isize>` [src]

#### `fn from_u16(n: u16) -> Option<isize>` [src]

#### `fn from_u32(n: u32) -> Option<isize>` [src]

#### `fn from_u64(n: u64) -> Option<isize>` [src]

#### `fn from_u128(n: u128) -> Option<isize>` [src]

#### `fn from_f32(n: f32) -> Option<isize>` [src]

#### `fn from_f64(n: f64) -> Option<isize>` [src]

### `impl FromPrimitive for u8` [src]

#### `fn from_isize(n: isize) -> Option<u8>` [src]

#### `fn from_i8(n: i8) -> Option<u8>` [src]

#### `fn from_i16(n: i16) -> Option<u8>` [src]

#### `fn from_i32(n: i32) -> Option<u8>` [src]

#### `fn from_i64(n: i64) -> Option<u8>` [src]

#### `fn from_i128(n: i128) -> Option<u8>` [src]

#### `fn from_usize(n: usize) -> Option<u8>` [src]

#### `fn from_u8(n: u8) -> Option<u8>` [src]

#### `fn from_u16(n: u16) -> Option<u8>` [src]

#### `fn from_u32(n: u32) -> Option<u8>` [src]

#### `fn from_u64(n: u64) -> Option<u8>` [src]

#### `fn from_u128(n: u128) -> Option<u8>` [src]

#### `fn from_f32(n: f32) -> Option<u8>` [src]

#### `fn from_f64(n: f64) -> Option<u8>` [src]

### `impl FromPrimitive for u16` [src]

#### `fn from_isize(n: isize) -> Option<u16>` [src]

#### `fn from_i8(n: i8) -> Option<u16>` [src]

#### `fn from_i16(n: i16) -> Option<u16>` [src]

#### `fn from_i32(n: i32) -> Option<u16>` [src]

#### `fn from_i64(n: i64) -> Option<u16>` [src]

#### `fn from_i128(n: i128) -> Option<u16>` [src]

#### `fn from_usize(n: usize) -> Option<u16>` [src]

#### `fn from_u8(n: u8) -> Option<u16>` [src]

#### `fn from_u16(n: u16) -> Option<u16>` [src]

#### `fn from_u32(n: u32) -> Option<u16>` [src]

#### `fn from_u64(n: u64) -> Option<u16>` [src]

#### `fn from_u128(n: u128) -> Option<u16>` [src]

#### `fn from_f32(n: f32) -> Option<u16>` [src]

#### `fn from_f64(n: f64) -> Option<u16>` [src]

### `impl FromPrimitive for u32` [src]

#### `fn from_isize(n: isize) -> Option<u32>` [src]

#### `fn from_i8(n: i8) -> Option<u32>` [src]

#### `fn from_i16(n: i16) -> Option<u32>` [src]

#### `fn from_i32(n: i32) -> Option<u32>` [src]

#### `fn from_i64(n: i64) -> Option<u32>` [src]

#### `fn from_i128(n: i128) -> Option<u32>` [src]

#### `fn from_usize(n: usize) -> Option<u32>` [src]

#### `fn from_u8(n: u8) -> Option<u32>` [src]

#### `fn from_u16(n: u16) -> Option<u32>` [src]

#### `fn from_u32(n: u32) -> Option<u32>` [src]

#### `fn from_u64(n: u64) -> Option<u32>` [src]

#### `fn from_u128(n: u128) -> Option<u32>` [src]

#### `fn from_f32(n: f32) -> Option<u32>` [src]

#### `fn from_f64(n: f64) -> Option<u32>` [src]

### `impl FromPrimitive for u64` [src]

#### `fn from_isize(n: isize) -> Option<u64>` [src]

#### `fn from_i8(n: i8) -> Option<u64>` [src]

#### `fn from_i16(n: i16) -> Option<u64>` [src]

#### `fn from_i32(n: i32) -> Option<u64>` [src]

#### `fn from_i64(n: i64) -> Option<u64>` [src]

#### `fn from_i128(n: i128) -> Option<u64>` [src]

#### `fn from_usize(n: usize) -> Option<u64>` [src]

#### `fn from_u8(n: u8) -> Option<u64>` [src]

#### `fn from_u16(n: u16) -> Option<u64>` [src]

#### `fn from_u32(n: u32) -> Option<u64>` [src]

#### `fn from_u64(n: u64) -> Option<u64>` [src]

#### `fn from_u128(n: u128) -> Option<u64>` [src]

#### `fn from_f32(n: f32) -> Option<u64>` [src]

#### `fn from_f64(n: f64) -> Option<u64>` [src]

### `impl FromPrimitive for u128` [src]

#### `fn from_isize(n: isize) -> Option<u128>` [src]

#### `fn from_i8(n: i8) -> Option<u128>` [src]

#### `fn from_i16(n: i16) -> Option<u128>` [src]

#### `fn from_i32(n: i32) -> Option<u128>` [src]

#### `fn from_i64(n: i64) -> Option<u128>` [src]

#### `fn from_i128(n: i128) -> Option<u128>` [src]

#### `fn from_usize(n: usize) -> Option<u128>` [src]

#### `fn from_u8(n: u8) -> Option<u128>` [src]

#### `fn from_u16(n: u16) -> Option<u128>` [src]

#### `fn from_u32(n: u32) -> Option<u128>` [src]

#### `fn from_u64(n: u64) -> Option<u128>` [src]

#### `fn from_u128(n: u128) -> Option<u128>` [src]

#### `fn from_f32(n: f32) -> Option<u128>` [src]

#### `fn from_f64(n: f64) -> Option<u128>` [src]

### `impl FromPrimitive for usize` [src]

#### `fn from_isize(n: isize) -> Option<usize>` [src]

#### `fn from_i8(n: i8) -> Option<usize>` [src]

#### `fn from_i16(n: i16) -> Option<usize>` [src]

#### `fn from_i32(n: i32) -> Option<usize>` [src]

#### `fn from_i64(n: i64) -> Option<usize>` [src]

#### `fn from_i128(n: i128) -> Option<usize>` [src]

#### `fn from_usize(n: usize) -> Option<usize>` [src]

#### `fn from_u8(n: u8) -> Option<usize>` [src]

#### `fn from_u16(n: u16) -> Option<usize>` [src]

#### `fn from_u32(n: u32) -> Option<usize>` [src]

#### `fn from_u64(n: u64) -> Option<usize>` [src]

#### `fn from_u128(n: u128) -> Option<usize>` [src]

#### `fn from_f32(n: f32) -> Option<usize>` [src]

#### `fn from_f64(n: f64) -> Option<usize>` [src]

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