Struct ethnum::U256 [−][src]
Expand description
A 256-bit unsigned integer type.
Tuple Fields
0: [u128; 2]
Implementations
The smallest value that can be represented by this integer type.
Examples
Basic usage:
assert_eq!(U256::MIN, U256::new(0));
The largest value that can be represented by this integer type.
Examples
Basic usage:
assert_eq!(
U256::MAX.to_string(),
"115792089237316195423570985008687907853269984665640564039457584007913129639935",
);
Converts a string slice in a given base to an integer.
The string is expected to be an optional +
sign followed by digits.
Leading and trailing whitespace represent an error. Digits are a subset
of these characters, depending on radix
:
0-9
a-z
A-Z
Panics
This function panics if radix
is not in the range from 2 to 36.
Examples
Basic usage:
assert_eq!(U256::from_str_radix("A", 16), Ok(U256::new(10)));
Returns the number of ones in the binary representation of self
.
Examples
Basic usage:
let n = U256::new(0b01001100);
assert_eq!(n.count_ones(), 3);
Returns the number of zeros in the binary representation of self
.
Examples
Basic usage:
assert_eq!(U256::MIN.count_zeros(), 256);
assert_eq!(U256::MAX.count_zeros(), 0);
Returns the number of leading zeros in the binary representation of
self
.
Examples
Basic usage:
let n = U256::MAX >> 2u32;
assert_eq!(n.leading_zeros(), 2);
Returns the number of trailing zeros in the binary representation of
self
.
Examples
Basic usage:
let n = U256::new(0b0101000);
assert_eq!(n.trailing_zeros(), 3);
Returns the number of leading ones in the binary representation of
self
.
Examples
Basic usage:
let n = !(U256::MAX >> 2u32);
assert_eq!(n.leading_ones(), 2);
Returns the number of trailing ones in the binary representation of
self
.
Examples
Basic usage:
let n = U256::new(0b1010111);
assert_eq!(n.trailing_ones(), 3);
Shifts the bits to the left by a specified amount, n
, wrapping the
truncated bits to the end of the resulting integer.
Please note this isn’t the same operation as the <<
shifting
operator!
Examples
Basic usage:
let n = U256::from_words(
0x13f40000000000000000000000000000,
0x00000000000000000000000000004f76,
);
let m = U256::new(0x4f7613f4);
assert_eq!(n.rotate_left(16), m);
Shifts the bits to the right by a specified amount, n
, wrapping the
truncated bits to the beginning of the resulting integer.
Please note this isn’t the same operation as the >>
shifting operator!
Examples
Basic usage:
let n = U256::new(0x4f7613f4);
let m = U256::from_words(
0x13f40000000000000000000000000000,
0x00000000000000000000000000004f76,
);
assert_eq!(n.rotate_right(16), m);
Reverses the byte order of the integer.
Examples
Basic usage:
let n = U256::from_words(
0x00010203_04050607_08090a0b_0c0d0e0f,
0x10111213_14151617_18191a1b_1c1d1e1f,
);
assert_eq!(
n.swap_bytes(),
U256::from_words(
0x1f1e1d1c_1b1a1918_17161514_13121110,
0x0f0e0d0c_0b0a0908_07060504_03020100,
),
);
Reverses the bit pattern of the integer.
Examples
Basic usage:
let n = U256::from_words(
0x00010203_04050607_08090a0b_0c0d0e0f,
0x10111213_14151617_18191a1b_1c1d1e1f,
);
assert_eq!(
n.reverse_bits(),
U256::from_words(
0xf878b838_d8589818_e868a828_c8488808,
0xf070b030_d0509010_e060a020_c0408000,
),
);
Converts an integer from big endian to the target’s endianness.
On big endian this is a no-op. On little endian the bytes are swapped.
Examples
Basic usage:
let n = U256::new(0x1A);
if cfg!(target_endian = "big") {
assert_eq!(U256::from_be(n), n);
} else {
assert_eq!(U256::from_be(n), n.swap_bytes());
}
Converts an integer from little endian to the target’s endianness.
On little endian this is a no-op. On big endian the bytes are swapped.
Examples
Basic usage:
let n = U256::new(0x1A);
if cfg!(target_endian = "little") {
assert_eq!(U256::from_le(n), n)
} else {
assert_eq!(U256::from_le(n), n.swap_bytes())
}
Converts self
to big endian from the target’s endianness.
On big endian this is a no-op. On little endian the bytes are swapped.
Examples
Basic usage:
let n = U256::new(0x1A);
if cfg!(target_endian = "big") {
assert_eq!(n.to_be(), n)
} else {
assert_eq!(n.to_be(), n.swap_bytes())
}
Converts self
to little endian from the target’s endianness.
On little endian this is a no-op. On big endian the bytes are swapped.
Examples
Basic usage:
let n = U256::new(0x1A);
if cfg!(target_endian = "little") {
assert_eq!(n.to_le(), n)
} else {
assert_eq!(n.to_le(), n.swap_bytes())
}
Checked integer addition. Computes self + rhs
, returning None
if
overflow occurred.
Examples
Basic usage:
assert_eq!((U256::MAX - 2).checked_add(U256::new(1)), Some(U256::MAX - 1));
assert_eq!((U256::MAX - 2).checked_add(U256::new(3)), None);
Checked integer subtraction. Computes self - rhs
, returning None
if
overflow occurred.
Examples
Basic usage:
assert_eq!(U256::new(1).checked_sub(U256::new(1)), Some(U256::ZERO));
assert_eq!(U256::new(0).checked_sub(U256::new(1)), None);
Checked integer multiplication. Computes self * rhs
, returning None
if overflow occurred.
Examples
Basic usage:
assert_eq!(U256::new(5).checked_mul(U256::new(1)), Some(U256::new(5)));
assert_eq!(U256::MAX.checked_mul(U256::new(2)), None);
Checked integer division. Computes self / rhs
, returning None
if
rhs == 0
.
Examples
Basic usage:
assert_eq!(U256::new(128).checked_div(U256::new(2)), Some(U256::new(64)));
assert_eq!(U256::new(1).checked_div(U256::new(0)), None);
Checked Euclidean division. Computes self.div_euclid(rhs)
, returning
None
if rhs == 0
.
Examples
Basic usage:
assert_eq!(U256::new(128).checked_div_euclid(U256::new(2)), Some(U256::new(64)));
assert_eq!(U256::new(1).checked_div_euclid(U256::new(0)), None);
Checked integer remainder. Computes self % rhs
, returning None
if
rhs == 0
.
Examples
Basic usage:
assert_eq!(U256::new(5).checked_rem(U256::new(2)), Some(U256::new(1)));
assert_eq!(U256::new(5).checked_rem(U256::new(0)), None);
Checked Euclidean modulo. Computes self.rem_euclid(rhs)
, returning
None
if rhs == 0
.
Examples
Basic usage:
assert_eq!(U256::new(5).checked_rem_euclid(U256::new(2)), Some(U256::new(1)));
assert_eq!(U256::new(5).checked_rem_euclid(U256::new(0)), None);
Checked negation. Computes -self
, returning None
unless self == 0
.
Note that negating any positive integer will overflow.
Examples
Basic usage:
assert_eq!(U256::ZERO.checked_neg(), Some(U256::ZERO));
assert_eq!(U256::new(1).checked_neg(), None);
Checked shift left. Computes self << rhs
, returning None
if rhs
is
larger than or equal to the number of bits in self
.
Examples
Basic usage:
assert_eq!(U256::new(0x1).checked_shl(4), Some(U256::new(0x10)));
assert_eq!(U256::new(0x10).checked_shl(257), None);
Checked shift right. Computes self >> rhs
, returning None
if rhs
is larger than or equal to the number of bits in self
.
Examples
Basic usage:
assert_eq!(U256::new(0x10).checked_shr(4), Some(U256::new(0x1)));
assert_eq!(U256::new(0x10).checked_shr(257), None);
Checked exponentiation. Computes self.pow(exp)
, returning None
if
overflow occurred.
Examples
Basic usage:
assert_eq!(U256::new(2).checked_pow(5), Some(U256::new(32)));
assert_eq!(U256::MAX.checked_pow(2), None);
Saturating integer addition. Computes self + rhs
, saturating at the
numeric bounds instead of overflowing.
Examples
Basic usage:
assert_eq!(U256::new(100).saturating_add(U256::new(1)), U256::new(101));
assert_eq!(U256::MAX.saturating_add(U256::new(127)), U256::MAX);
Saturating integer subtraction. Computes self - rhs
, saturating at the
numeric bounds instead of overflowing.
Examples
Basic usage:
assert_eq!(U256::new(100).saturating_sub(U256::new(27)), U256::new(73));
assert_eq!(U256::new(13).saturating_sub(U256::new(127)), U256::new(0));
Saturating integer multiplication. Computes self * rhs
, saturating at
the numeric bounds instead of overflowing.
Examples
Basic usage:
assert_eq!(U256::new(2).saturating_mul(U256::new(10)), U256::new(20));
assert_eq!((U256::MAX).saturating_mul(U256::new(10)), U256::MAX);
Saturating integer exponentiation. Computes self.pow(exp)
, saturating
at the numeric bounds instead of overflowing.
Examples
Basic usage:
assert_eq!(U256::new(4).saturating_pow(3), U256::new(64));
assert_eq!(U256::MAX.saturating_pow(2), U256::MAX);
Wrapping (modular) addition. Computes self + rhs
, wrapping around at
the boundary of the type.
Examples
Basic usage:
assert_eq!(U256::new(200).wrapping_add(U256::new(55)), U256::new(255));
assert_eq!(U256::new(200).wrapping_add(U256::MAX), U256::new(199));
Wrapping (modular) subtraction. Computes self - rhs
, wrapping around
at the boundary of the type.
Examples
Basic usage:
assert_eq!(U256::new(100).wrapping_sub(U256::new(100)), U256::new(0));
assert_eq!(U256::new(100).wrapping_sub(U256::MAX), U256::new(101));
Wrapping (modular) multiplication. Computes self * rhs
, wrapping
around at the boundary of the type.
Examples
Basic usage:
Please note that this example is shared between integer types.
Which explains why u8
is used here.
assert_eq!(U256::new(10).wrapping_mul(U256::new(12)), U256::new(120));
assert_eq!(U256::MAX.wrapping_mul(U256::new(2)), U256::MAX - 1);
Wrapping (modular) division. Computes self / rhs
. Wrapped division on
unsigned types is just normal division. There’s no way wrapping could
ever happen. This function exists, so that all operations are accounted
for in the wrapping operations.
Examples
Basic usage:
assert_eq!(U256::new(100).wrapping_div(U256::new(10)), U256::new(10));
Wrapping Euclidean division. Computes self.div_euclid(rhs)
. Wrapped
division on unsigned types is just normal division. There’s no way
wrapping could ever happen. This function exists, so that all operations
are accounted for in the wrapping operations. Since, for the positive
integers, all common definitions of division are equal, this is exactly
equal to self.wrapping_div(rhs)
.
Examples
Basic usage:
assert_eq!(U256::new(100).wrapping_div_euclid(U256::new(10)), U256::new(10));
Wrapping (modular) remainder. Computes self % rhs
. Wrapped remainder
calculation on unsigned types is just the regular remainder calculation.
There’s no way wrapping could ever happen. This function exists, so that
all operations are accounted for in the wrapping operations.
Examples
Basic usage:
assert_eq!(U256::new(100).wrapping_rem(U256::new(10)), U256::new(0));
Wrapping Euclidean modulo. Computes self.rem_euclid(rhs)
. Wrapped
modulo calculation on unsigned types is just the regular remainder
calculation. There’s no way wrapping could ever happen. This function
exists, so that all operations are accounted for in the wrapping
operations. Since, for the positive integers, all common definitions of
division are equal, this is exactly equal to self.wrapping_rem(rhs)
.
Examples
Basic usage:
assert_eq!(U256::new(100).wrapping_rem_euclid(U256::new(10)), U256::new(0));
Wrapping (modular) negation. Computes -self
, wrapping around at the
boundary of the type.
Since unsigned types do not have negative equivalents all applications
of this function will wrap (except for -0
). For values smaller than
the corresponding signed type’s maximum the result is the same as
casting the corresponding signed value. Any larger values are equivalent
to MAX + 1 - (val - MAX - 1)
where MAX
is the corresponding signed
type’s maximum.
Examples
Basic usage:
Please note that this example is shared between integer types.
Which explains why i8
is used here.
assert_eq!(U256::new(100).wrapping_neg(), (-100i128).as_u256());
assert_eq!(
U256::from_words(i128::MIN as _, 0).wrapping_neg(),
U256::from_words(i128::MIN as _, 0),
);
Panic-free bitwise shift-left; yields self << mask(rhs)
, where mask
removes any high-order bits of rhs
that would cause the shift to
exceed the bitwidth of the type.
Note that this is not the same as a rotate-left; the RHS of a wrapping
shift-left is restricted to the range of the type, rather than the bits
shifted out of the LHS being returned to the other end. The primitive
integer types all implement a rotate_left
function, which maybe what
you want instead.
Examples
Basic usage:
assert_eq!(U256::new(1).wrapping_shl(7), U256::new(128));
assert_eq!(U256::new(1).wrapping_shl(128), U256::from_words(1, 0));
assert_eq!(U256::new(1).wrapping_shl(256), U256::new(1));
Panic-free bitwise shift-right; yields self >> mask(rhs)
, where mask
removes any high-order bits of rhs
that would cause the shift to
exceed the bitwidth of the type.
Note that this is not the same as a rotate-right; the RHS of a
wrapping shift-right is restricted to the range of the type, rather than
the bits shifted out of the LHS being returned to the other end. The
primitive integer types all implement a rotate_right
function, which
may be what you want instead.
Examples
Basic usage:
assert_eq!(U256::new(128).wrapping_shr(7), U256::new(1));
assert_eq!(U256::from_words(128, 0).wrapping_shr(128), U256::new(128));
assert_eq!(U256::new(128).wrapping_shr(256), U256::new(128));
Wrapping (modular) exponentiation. Computes self.pow(exp)
, wrapping
around at the boundary of the type.
Examples
Basic usage:
assert_eq!(U256::new(3).wrapping_pow(5), U256::new(243));
assert_eq!(
U256::new(1337).wrapping_pow(42),
U256::from_words(
45367329835866155830012179193722278514,
159264946433345088039815329994094210673,
),
);
Calculates self
+ rhs
Returns a tuple of the addition along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.
Examples
Basic usage
assert_eq!(U256::new(5).overflowing_add(U256::new(2)), (U256::new(7), false));
assert_eq!(U256::MAX.overflowing_add(U256::new(1)), (U256::new(0), true));
Calculates self
- rhs
Returns a tuple of the subtraction along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.
Examples
Basic usage
assert_eq!(U256::new(5).overflowing_sub(U256::new(2)), (U256::new(3), false));
assert_eq!(U256::new(0).overflowing_sub(U256::new(1)), (U256::MAX, true));
Calculates the multiplication of self
and rhs
.
Returns a tuple of the multiplication along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.
Examples
Basic usage:
Please note that this example is shared between integer types.
Which explains why u32
is used here.
assert_eq!(U256::new(5).overflowing_mul(U256::new(2)), (U256::new(10), false));
assert_eq!(
U256::MAX.overflowing_mul(U256::new(2)),
(U256::MAX - 1, true),
);
Calculates the divisor when self
is divided by rhs
.
Returns a tuple of the divisor along with a boolean indicating whether
an arithmetic overflow would occur. Note that for unsigned integers
overflow never occurs, so the second value is always false
.
Panics
This function will panic if rhs
is 0.
Examples
Basic usage
assert_eq!(U256::new(5).overflowing_div(U256::new(2)), (U256::new(2), false));
Calculates the quotient of Euclidean division self.div_euclid(rhs)
.
Returns a tuple of the divisor along with a boolean indicating whether
an arithmetic overflow would occur. Note that for unsigned integers
overflow never occurs, so the second value is always false
. Since,
for the positive integers, all common definitions of division are equal,
this is exactly equal to self.overflowing_div(rhs)
.
Panics
This function will panic if rhs
is 0.
Examples
Basic usage
assert_eq!(U256::new(5).overflowing_div_euclid(U256::new(2)), (U256::new(2), false));
Calculates the remainder when self
is divided by rhs
.
Returns a tuple of the remainder after dividing along with a boolean
indicating whether an arithmetic overflow would occur. Note that for
unsigned integers overflow never occurs, so the second value is always
false
.
Panics
This function will panic if rhs
is 0.
Examples
Basic usage
assert_eq!(U256::new(5).overflowing_rem(U256::new(2)), (U256::new(1), false));
Calculates the remainder self.rem_euclid(rhs)
as if by Euclidean
division.
Returns a tuple of the modulo after dividing along with a boolean
indicating whether an arithmetic overflow would occur. Note that for
unsigned integers overflow never occurs, so the second value is always
false
. Since, for the positive integers, all common definitions of
division are equal, this operation is exactly equal to
self.overflowing_rem(rhs)
.
Panics
This function will panic if rhs
is 0.
Examples
Basic usage
assert_eq!(U256::new(5).overflowing_rem_euclid(U256::new(2)), (U256::new(1), false));
Negates self in an overflowing fashion.
Returns !self + 1
using wrapping operations to return the value that
represents the negation of this unsigned value. Note that for positive
unsigned values overflow always occurs, but negating 0 does not
overflow.
Examples
Basic usage
assert_eq!(U256::new(0).overflowing_neg(), (U256::new(0), false));
assert_eq!(U256::new(2).overflowing_neg(), ((-2i32).as_u256(), true));
Shifts self left by rhs
bits.
Returns a tuple of the shifted version of self along with a boolean indicating whether the shift value was larger than or equal to the number of bits. If the shift value is too large, then value is masked (N-1) where N is the number of bits, and this value is then used to perform the shift.
Examples
Basic usage
assert_eq!(U256::new(0x1).overflowing_shl(4), (U256::new(0x10), false));
assert_eq!(U256::new(0x1).overflowing_shl(260), (U256::new(0x10), true));
Shifts self right by rhs
bits.
Returns a tuple of the shifted version of self along with a boolean indicating whether the shift value was larger than or equal to the number of bits. If the shift value is too large, then value is masked (N-1) where N is the number of bits, and this value is then used to perform the shift.
Examples
Basic usage
assert_eq!(U256::new(0x10).overflowing_shr(4), (U256::new(0x1), false));
assert_eq!(U256::new(0x10).overflowing_shr(260), (U256::new(0x1), true));
Raises self to the power of exp
, using exponentiation by squaring.
Returns a tuple of the exponentiation along with a bool indicating whether an overflow happened.
Examples
Basic usage:
assert_eq!(U256::new(3).overflowing_pow(5), (U256::new(243), false));
assert_eq!(
U256::new(1337).overflowing_pow(42),
(
U256::from_words(
45367329835866155830012179193722278514,
159264946433345088039815329994094210673,
),
true,
)
);
Raises self to the power of exp
, using exponentiation by squaring.
Examples
Basic usage:
assert_eq!(U256::new(2).pow(5), U256::new(32));
Returns true
if and only if self == 2^k
for some k
.
Examples
Basic usage:
assert!(U256::new(16).is_power_of_two());
assert!(!U256::new(10).is_power_of_two());
Returns the smallest power of two greater than or equal to self
.
When return value overflows (i.e., self > (1 << (N-1))
for type uN
),
it panics in debug mode and return value is wrapped to 0 in release mode
(the only situation in which method can return 0).
Examples
Basic usage:
assert_eq!(U256::new(2).next_power_of_two(), U256::new(2));
assert_eq!(U256::new(3).next_power_of_two(), U256::new(4));
Returns the smallest power of two greater than or equal to n
. If the
next power of two is greater than the type’s maximum value, None
is
returned, otherwise the power of two is wrapped in Some
.
Examples
Basic usage:
assert_eq!(U256::new(2).checked_next_power_of_two(), Some(U256::new(2)));
assert_eq!(U256::new(3).checked_next_power_of_two(), Some(U256::new(4)));
assert_eq!(U256::MAX.checked_next_power_of_two(), None);
Return the memory representation of this integer as a byte array in big endian (network) byte order.
Examples
let bytes = U256::from_words(
0x00010203_04050607_08090a0b_0c0d0e0f,
0x10111213_14151617_18191a1b_1c1d1e1f,
);
assert_eq!(
bytes.to_be_bytes(),
[
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
],
);
Return the memory representation of this integer as a byte array in little endian byte order.
Examples
let bytes = U256::from_words(
0x00010203_04050607_08090a0b_0c0d0e0f,
0x10111213_14151617_18191a1b_1c1d1e1f,
);
assert_eq!(
bytes.to_le_bytes(),
[
0x1f, 0x1e, 0x1d, 0x1c, 0x1b, 0x1a, 0x19, 0x18, 0x17, 0x16, 0x15, 0x14, 0x13, 0x12, 0x11, 0x10,
0x0f, 0x0e, 0x0d, 0x0c, 0x0b, 0x0a, 0x09, 0x08, 0x07, 0x06, 0x05, 0x04, 0x03, 0x02, 0x01, 0x00,
],
);
Return the memory representation of this integer as a byte array in native byte order.
As the target platform’s native endianness is used, portable code should
use to_be_bytes
or to_le_bytes
, as appropriate, instead.
Examples
let bytes = U256::from_words(
0x00010203_04050607_08090a0b_0c0d0e0f,
0x10111213_14151617_18191a1b_1c1d1e1f,
);
assert_eq!(
bytes.to_ne_bytes(),
if cfg!(target_endian = "big") {
[
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
]
} else {
[
0x1f, 0x1e, 0x1d, 0x1c, 0x1b, 0x1a, 0x19, 0x18, 0x17, 0x16, 0x15, 0x14, 0x13, 0x12, 0x11, 0x10,
0x0f, 0x0e, 0x0d, 0x0c, 0x0b, 0x0a, 0x09, 0x08, 0x07, 0x06, 0x05, 0x04, 0x03, 0x02, 0x01, 0x00,
]
}
);
Create an integer value from its representation as a byte array in big endian.
Examples
let value = U256::from_be_bytes([
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
]);
assert_eq!(
value,
U256::from_words(
0x00010203_04050607_08090a0b_0c0d0e0f,
0x10111213_14151617_18191a1b_1c1d1e1f,
),
);
When starting from a slice rather than an array, fallible conversion APIs can be used:
use std::convert::TryInto;
fn read_be_U256(input: &mut &[u8]) -> U256 {
let (int_bytes, rest) = input.split_at(std::mem::size_of::<U256>());
*input = rest;
U256::from_be_bytes(int_bytes.try_into().unwrap())
}
Create an integer value from its representation as a byte array in little endian.
Examples
let value = U256::from_le_bytes([
0x1f, 0x1e, 0x1d, 0x1c, 0x1b, 0x1a, 0x19, 0x18, 0x17, 0x16, 0x15, 0x14, 0x13, 0x12, 0x11, 0x10,
0x0f, 0x0e, 0x0d, 0x0c, 0x0b, 0x0a, 0x09, 0x08, 0x07, 0x06, 0x05, 0x04, 0x03, 0x02, 0x01, 0x00,
]);
assert_eq!(
value,
U256::from_words(
0x00010203_04050607_08090a0b_0c0d0e0f,
0x10111213_14151617_18191a1b_1c1d1e1f,
),
);
When starting from a slice rather than an array, fallible conversion APIs can be used:
use std::convert::TryInto;
fn read_be_U256(input: &mut &[u8]) -> U256 {
let (int_bytes, rest) = input.split_at(std::mem::size_of::<U256>());
*input = rest;
U256::from_le_bytes(int_bytes.try_into().unwrap())
}
Create an integer value from its memory representation as a byte array in native endianness.
As the target platform’s native endianness is used, portable code likely
wants to use from_be_bytes
or from_le_bytes
, as appropriate
instead.
Examples
let value = U256::from_ne_bytes(if cfg!(target_endian = "big") {
[
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
]
} else {
[
0x1f, 0x1e, 0x1d, 0x1c, 0x1b, 0x1a, 0x19, 0x18, 0x17, 0x16, 0x15, 0x14, 0x13, 0x12, 0x11, 0x10,
0x0f, 0x0e, 0x0d, 0x0c, 0x0b, 0x0a, 0x09, 0x08, 0x07, 0x06, 0x05, 0x04, 0x03, 0x02, 0x01, 0x00,
]
});
assert_eq!(
value,
U256::from_words(
0x00010203_04050607_08090a0b_0c0d0e0f,
0x10111213_14151617_18191a1b_1c1d1e1f,
),
);
When starting from a slice rather than an array, fallible conversion APIs can be used:
use std::convert::TryInto;
fn read_be_U256(input: &mut &[u8]) -> U256 {
let (int_bytes, rest) = input.split_at(std::mem::size_of::<U256>());
*input = rest;
U256::from_ne_bytes(int_bytes.try_into().unwrap())
}
Creates a new 256-bit integer value from a primitive u128
integer.
Creates a new 256-bit integer value from high and low words.
Get the low 128-bit word for this unsigned integer as a mutable reference.
Get the high 128-bit word for this unsigned integer as a mutable reference.
Trait Implementations
Performs the +=
operation. Read more
Performs the +=
operation. Read more
Performs the +=
operation. Read more
Performs the +=
operation. Read more
Performs the &=
operation. Read more
Performs the &=
operation. Read more
Performs the &=
operation. Read more
Performs the &=
operation. Read more
Performs the |=
operation. Read more
Performs the |=
operation. Read more
Performs the |=
operation. Read more
Performs the |=
operation. Read more
Performs the ^=
operation. Read more
Performs the ^=
operation. Read more
Performs the ^=
operation. Read more
Performs the ^=
operation. Read more
Performs the /=
operation. Read more
Performs the /=
operation. Read more
Performs the /=
operation. Read more
Performs the /=
operation. Read more
Performs the *=
operation. Read more
Performs the *=
operation. Read more
Performs the *=
operation. Read more
Performs the *=
operation. Read more
This method returns an ordering between self
and other
values if one exists. Read more
This method tests less than (for self
and other
) and is used by the <
operator. Read more
This method tests less than or equal to (for self
and other
) and is used by the <=
operator. Read more
This method tests greater than (for self
and other
) and is used by the >
operator. Read more
This method returns an ordering between self
and other
values if one exists. Read more
This method tests less than (for self
and other
) and is used by the <
operator. Read more
This method tests less than or equal to (for self
and other
) and is used by the <=
operator. Read more
This method tests greater than (for self
and other
) and is used by the >
operator. Read more
Performs the %=
operation. Read more
Performs the %=
operation. Read more
Performs the %=
operation. Read more
Performs the %=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the <<=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the >>=
operation. Read more
Performs the -=
operation. Read more
Performs the -=
operation. Read more
Performs the -=
operation. Read more
Performs the -=
operation. Read more