protocol
FixedWidthInteger
An integer type that uses a fixed size for every instance.
Inheritance | BinaryInteger, LosslessStringConvertible |
---|---|
Conforming Types | Int, Int16, Int32, Int64, Int8, UInt, UInt16, UInt32, UInt64, UInt8 |
Initializers
Creates an integer from its big-endian representation, changing the byte order if necessary.
- Parameter value: A value to use as the big-endian representation of the new integer.
Declaration
init
(
bigEndian
value
:
Self
)
Creates an integer from its little-endian representation, changing the byte order if necessary.
- Parameter value: A value to use as the little-endian representation of the new integer.
Declaration
init
(
littleEndian
value
:
Self
)
Instance Variables
The big-endian representation of this integer.
If necessary, the byte order of this value is reversed from the typical
byte order of this integer type. On a big-endian platform, for any
integer x
, x == x.bigEndian
.
Declaration
var
bigEndian
:
Self
A representation of this integer with the byte order swapped.
Declaration
var
byteSwapped
:
Self
The number of leading zeros in this value's binary representation.
For example, in a fixed-width integer type with a bitWidth
value of 8,
the number 31 has three leading zeros.
let
x
:
Int8
=
0b0001_1111
// x == 31
// x.leadingZeroBitCount == 3
If the value is zero, then leadingZeroBitCount
is equal to bitWidth
.
Declaration
var
leadingZeroBitCount
:
Int
The little-endian representation of this integer.
If necessary, the byte order of this value is reversed from the typical
byte order of this integer type. On a little-endian platform, for any
integer x
, x == x.littleEndian
.
Declaration
var
littleEndian
:
Self
Instance Methods
Returns the sum of this value and the given value, along with a Boolean value indicating whether overflow occurred in the operation.
- Parameter rhs: The value to add to this value.
Declaration
func
addingReportingOverflow
(
_
rhs
:
Self
) -
>
(
partialValue
:
Self
,
overflow
:
Bool
)
Returns the quotient obtained by dividing this value by the given value, along with a Boolean value indicating whether overflow occurred in the operation.
Dividing by zero is not an error when using this method. For a value x
,
the result of x.dividedReportingOverflow(by: 0)
is (x, true)
.
- Parameter rhs: The value to divide this value by.
Declaration
func
dividedReportingOverflow
(
by
rhs
:
Self
) -
>
(
partialValue
:
Self
,
overflow
:
Bool
)
Returns a tuple containing the quotient and remainder obtained by dividing the given value by this value.
The resulting quotient must be representable within the bounds of the type. If the quotient is too large to represent in the type, a runtime error may occur.
The following example divides a value that is too large to be represented
using a single Int
instance by another Int
value. Because the quotient
is representable as an Int
, the division succeeds.
// 'dividend' represents the value 0x506f70652053616e74612049494949
let
dividend
= (
22640526660490081
,
7959093232766896457
as
UInt
)
let
divisor
=
2241543570477705381
let
(
quotient
,
remainder
) =
divisor
.
dividingFullWidth
(
dividend
)
// quotient == 186319822866995413
// remainder == 0
- Parameter dividend: A tuple containing the high and low parts of a double-width integer.
Declaration
func
dividingFullWidth
(
_
dividend
: (
high
:
Self
,
low
:
Self
.
Magnitude
)) -
>
(
quotient
:
Self
,
remainder
:
Self
)
Returns a tuple containing the high and low parts of the result of multiplying this value by the given value.
Use this method to calculate the full result of a product that would
otherwise overflow. Unlike traditional truncating multiplication, the
multipliedFullWidth(by:)
method returns a tuple containing both the
high
and low
parts of the product of this value and other
. The
following example uses this method to multiply two Int8
values that
normally overflow when multiplied:
The product of x
and y
is -1920
, which is too large to represent in
an Int8
instance. The high
and low
compnents of the result
value
represent -1920
when concatenated to form a double-width integer; that
is, using result.high
as the high byte and result.low
as the low byte
of an Int16
instance.
- Parameter other: The value to multiply this value by.
Declaration
func
multipliedFullWidth
(
by
other
:
Self
) -
>
(
high
:
Self
,
low
:
Self
.
Magnitude
)
Returns the product of this value and the given value, along with a Boolean value indicating whether overflow occurred in the operation.
- Parameter rhs: The value to multiply by this value.
Declaration
func
multipliedReportingOverflow
(
by
rhs
:
Self
) -
>
(
partialValue
:
Self
,
overflow
:
Bool
)
Returns the remainder after dividing this value by the given value, along with a Boolean value indicating whether overflow occurred during division.
Dividing by zero is not an error when using this method. For a value x
,
the result of x.remainderReportingOverflow(dividingBy: 0)
is
(x, true)
.
- Parameter rhs: The value to divide this value by.
Declaration
func
remainderReportingOverflow
(
dividingBy
rhs
:
Self
) -
>
(
partialValue
:
Self
,
overflow
:
Bool
)
Returns the difference obtained by subtracting the given value from this value, along with a Boolean value indicating whether overflow occurred in the operation.
- Parameter rhs: The value to subtract from this value.
Declaration
func
subtractingReportingOverflow
(
_
rhs
:
Self
) -
>
(
partialValue
:
Self
,
overflow
:
Bool
)
Type Variables
The number of bits used for the underlying binary representation of values of this type.
An unsigned, fixed-width integer type can represent values from 0 through
(2 ** bitWidth) - 1
, where **
is exponentiation. A signed,
fixed-width integer type can represent values from
-(2 ** (bitWidth - 1))
through (2 ** (bitWidth - 1)) - 1
. For example,
the Int8
type has a bitWidth
value of 8 and can store any integer in
the range -128...127
.
Declaration
var
bitWidth
:
Int
The maximum representable integer in this type.
For unsigned integer types, this value is (2 ** bitWidth) - 1
, where
**
is exponentiation. For signed integer types, this value is
(2 ** (bitWidth - 1)) - 1
.
Declaration
var
max
:
Self
The minimum representable integer in this type.
For unsigned integer types, this value is always 0
. For signed integer
types, this value is -(2 ** (bitWidth - 1))
, where **
is
exponentiation.
Declaration
var
min
:
Self
Type Methods
Returns the result of shifting a value's binary representation the specified number of digits to the left, masking the shift amount to the type's bit width.
Use the masking left shift operator (&<<
) when you need to perform a
shift and are sure that the shift amount is in the range
0..<lhs.bitWidth
. Before shifting, the masking left shift operator
masks the shift to this range. The shift is performed using this masked
value.
The following example defines x
as an instance of UInt8
, an 8-bit,
unsigned integer type. If you use 2
as the right-hand-side value in an
operation on x
, the shift amount requires no masking.
let
x
:
UInt8
=
30
// 0b00011110
let
y
=
x
&
<
<
2
// y == 120 // 0b01111000
However, if you use 8
as the shift amount, the method first masks the
shift amount to zero, and then performs the shift, resulting in no change
to the original value.
let
z
=
x
&
<
<
8
// z == 30 // 0b00011110
If the bit width of the shifted integer type is a power of two, masking is performed using a bitmask; otherwise, masking is performed using a modulo operation.
Declaration
static
func
&
<
<
(
lhs
:
Self
,
rhs
:
Self
) -
>
Self
Returns the result of shifting a value's binary representation the specified number of digits to the left, masking the shift amount to the type's bit width, and stores the result in the left-hand-side variable.
The &<<=
operator performs a masking shift, where the value used as
rhs
is masked to produce a value in the range 0..<lhs.bitWidth
. The
shift is performed using this masked value.
The following example defines x
as an instance of UInt8
, an 8-bit,
unsigned integer type. If you use 2
as the right-hand-side value in an
operation on x
, the shift amount requires no masking.
var
x
:
UInt8
=
30
// 0b00011110
x
&
<
<
=
2
// x == 120 // 0b01111000
However, if you pass 19
as rhs
, the method first bitmasks rhs
to
3
, and then uses that masked value as the number of bits to shift lhs
.
var
y
:
UInt8
=
30
// 0b00011110
y
&
<
<
=
19
// y == 240 // 0b11110000
Declaration
static
func
&
<
<
=(
lhs
:
inout
Self
,
rhs
:
Self
)
Returns the result of shifting a value's binary representation the specified number of digits to the right, masking the shift amount to the type's bit width.
Use the masking right shift operator (&>>
) when you need to perform a
shift and are sure that the shift amount is in the range
0..<lhs.bitWidth
. Before shifting, the masking right shift operator
masks the shift to this range. The shift is performed using this masked
value.
The following example defines x
as an instance of UInt8
, an 8-bit,
unsigned integer type. If you use 2
as the right-hand-side value in an
operation on x
, the shift amount requires no masking.
let
x
:
UInt8
=
30
// 0b00011110
let
y
=
x
&
>
>
2
// y == 7 // 0b00000111
However, if you use 8
as the shift amount, the method first masks the
shift amount to zero, and then performs the shift, resulting in no change
to the original value.
let
z
=
x
&
>
>
8
// z == 30 // 0b00011110
If the bit width of the shifted integer type is a power of two, masking is performed using a bitmask; otherwise, masking is performed using a modulo operation.
Declaration
static
func
&
>
>
(
lhs
:
Self
,
rhs
:
Self
) -
>
Self
Calculates the result of shifting a value's binary representation the specified number of digits to the right, masking the shift amount to the type's bit width, and stores the result in the left-hand-side variable.
The &>>=
operator performs a masking shift, where the value passed as
rhs
is masked to produce a value in the range 0..<lhs.bitWidth
. The
shift is performed using this masked value.
The following example defines x
as an instance of UInt8
, an 8-bit,
unsigned integer type. If you use 2
as the right-hand-side value in an
operation on x
, the shift amount requires no masking.
var
x
:
UInt8
=
30
// 0b00011110
x
&
>
>
=
2
// x == 7 // 0b00000111
However, if you use 19
as rhs
, the operation first bitmasks rhs
to
3
, and then uses that masked value as the number of bits to shift lhs
.
var
y
:
UInt8
=
30
// 0b00011110
y
&
>
>
=
19
// y == 3 // 0b00000011
Declaration
static
func
&
>
>
=(
lhs
:
inout
Self
,
rhs
:
Self
)
Default Implementations
Returns a Boolean value indicating whether the two given values are not equal.
You can check the inequality of instances of any BinaryInteger
types
using the not-equal-to operator (!=
). For example, you can test
whether the first UInt8
value in a string's UTF-8 encoding is not
equal to the first UInt32
value in its Unicode scalar view:
let
gameName
=
"Red Light, Green Light"
if
let
firstUTF8
=
gameName
.
utf8
.
first
,
let
firstScalar
=
gameName
.
unicodeScalars
.
first
?.
value
{
(
"First code values are different: \(
firstUTF8
!=
firstScalar
)"
)
}
// Prints "First code values are different: false"
Declaration
public
static
func
!=
<
Other
>
(
lhs
:
Self
,
rhs
:
Other
) -
>
Bool
where
Other
:
BinaryInteger
Declaration
public
static
func
!=(
lhs
:
Self
,
rhs
:
Self
) -
>
Bool
Returns the result of performing a bitwise AND operation on the two given values.
A bitwise AND operation results in a value that has each bit set to 1
where both of its arguments have that bit set to 1
. For example:
Declaration
public
static
func
&
(
lhs
:
Self
,
rhs
:
Self
) -
>
Self
Returns a Boolean value indicating whether the value of the first argument is less than that of the second argument.
You can compare instances of any BinaryInteger
types using the
less-than operator (<
), even if the two instances are of different
types.
Declaration
public
static
func
<
<
Other
>
(
lhs
:
Self
,
rhs
:
Other
) -
>
Bool
where
Other
:
BinaryInteger
Returns the result of shifting a value's binary representation the specified number of digits to the left.
The <<
operator performs a smart shift, which defines a result for a
shift of any value.
The following example defines x
as an instance of UInt8
, an 8-bit,
unsigned integer type. If you use 2
as the right-hand-side value in an
operation on x
, the value is shifted left by two bits.
let
x
:
UInt8
=
30
// 0b00011110
let
y
=
x
<
<
2
// y == 120 // 0b01111000
If you use 11
as rhs
, x
is overshifted such that all of its bits
are set to zero.
let
z
=
x
<
<
11
// z == 0 // 0b00000000
Using a negative value as rhs
is the same as performing a right shift
with abs(rhs)
.
let
a
=
x
<
<
-
3
// a == 3 // 0b00000011
let
b
=
x
>
>
3
// b == 3 // 0b00000011
Declaration
public
static
func
<
<
<
RHS
>
(
lhs
:
Self
,
rhs
:
RHS
) -
>
Self
where
RHS
:
BinaryInteger
Returns a Boolean value indicating whether the value of the first argument is less than or equal to that of the second argument.
You can compare instances of any BinaryInteger
types using the
less-than-or-equal-to operator (<=
), even if the two instances are of
different types.
Declaration
public
static
func
<
=
<
Other
>
(
lhs
:
Self
,
rhs
:
Other
) -
>
Bool
where
Other
:
BinaryInteger
Returns a Boolean value indicating whether the value of the first argument is less than or equal to that of the second argument.
Declaration
public
static
func
<
=(
lhs
:
Self
,
rhs
:
Self
) -
>
Bool
Returns a Boolean value indicating whether the two given values are equal.
You can check the equality of instances of any BinaryInteger
types
using the equal-to operator (==
). For example, you can test whether
the first UInt8
value in a string's UTF-8 encoding is equal to the
first UInt32
value in its Unicode scalar view:
let
gameName
=
"Red Light, Green Light"
if
let
firstUTF8
=
gameName
.
utf8
.
first
,
let
firstScalar
=
gameName
.
unicodeScalars
.
first
?.
value
{
(
"First code values are equal: \(
firstUTF8
==
firstScalar
)"
)
}
// Prints "First code values are equal: true"
Declaration
public
static
func
==
<
Other
>
(
lhs
:
Self
,
rhs
:
Other
) -
>
Bool
where
Other
:
BinaryInteger
Returns a Boolean value indicating whether the value of the first argument is greater than that of the second argument.
You can compare instances of any BinaryInteger
types using the
greater-than operator (>
), even if the two instances are of different
types.
Declaration
public
static
func
>
<
Other
>
(
lhs
:
Self
,
rhs
:
Other
) -
>
Bool
where
Other
:
BinaryInteger
Returns a Boolean value indicating whether the value of the first argument is greater than that of the second argument.
Declaration
public
static
func
>
(
lhs
:
Self
,
rhs
:
Self
) -
>
Bool
Returns a Boolean value indicating whether the value of the first argument is greater than or equal to that of the second argument.
You can compare instances of any BinaryInteger
types using the
greater-than-or-equal-to operator (>=
), even if the two instances are
of different types.
Declaration
public
static
func
>
=
<
Other
>
(
lhs
:
Self
,
rhs
:
Other
) -
>
Bool
where
Other
:
BinaryInteger
Returns a Boolean value indicating whether the value of the first argument is greater than or equal to that of the second argument.
Declaration
public
static
func
>
=(
lhs
:
Self
,
rhs
:
Self
) -
>
Bool
Returns the result of shifting a value's binary representation the specified number of digits to the right.
The >>
operator performs a smart shift, which defines a result for a
shift of any value.
The following example defines x
as an instance of UInt8
, an 8-bit,
unsigned integer type. If you use 2
as the right-hand-side value in an
operation on x
, the value is shifted right by two bits.
let
x
:
UInt8
=
30
// 0b00011110
let
y
=
x
>
>
2
// y == 7 // 0b00000111
If you use 11
as rhs
, x
is overshifted such that all of its bits
are set to zero.
let
z
=
x
>
>
11
// z == 0 // 0b00000000
Using a negative value as rhs
is the same as performing a left shift
using abs(rhs)
.
let
a
=
x
>
>
-
3
// a == 240 // 0b11110000
let
b
=
x
<
<
3
// b == 240 // 0b11110000
Right shift operations on negative values "fill in" the high bits with ones instead of zeros.
let
q
:
Int8
= -
30
// 0b11100010
let
r
=
q
>
>
2
// r == -8 // 0b11111000
let
s
=
q
>
>
11
// s == -1 // 0b11111111
Declaration
public
static
func
>
>
<
RHS
>
(
lhs
:
Self
,
rhs
:
RHS
) -
>
Self
where
RHS
:
BinaryInteger
Returns the result of performing a bitwise XOR operation on the two given values.
A bitwise XOR operation, also known as an exclusive OR operation, results
in a value that has each bit set to 1
where one or the other but not
both of its arguments had that bit set to 1
. For example:
Declaration
public
static
func
^(
lhs
:
Self
,
rhs
:
Self
) -
>
Self
Returns a value that is offset the specified distance from this value.
Use the advanced(by:)
method in generic code to offset a value by a
specified distance. If you're working directly with numeric values, use
the addition operator (+
) instead of this method.
For a value x
, a distance n
, and a value y = x.advanced(by: n)
,
x.distance(to: y) == n
.
- Parameter n: The distance to advance this value.
Declaration
@
inlinable
public
func
advanced
(
by
n
:
Int
) -
>
Self
Returns the distance from this value to the given value, expressed as a stride.
For two values x
and y
, and a distance n = x.distance(to: y)
,
x.advanced(by: n) == y
.
- Parameter other: The value to calculate the distance to.
Declaration
@
inlinable
public
func
distance
(
to
other
:
Self
) -
>
Int
Creates a new value equal to zero.
Declaration
public
init
()
Returns true
if this value is a multiple of the given value, and false
otherwise.
For two integers a and b, a is a multiple of b if there exists a third integer q such that a = q*b. For example, 6 is a multiple of 3 because 6 = 2*3. Zero is a multiple of everything because 0 = 0*x for any integer x.
Two edge cases are worth particular attention:
- Parameter other: The value to test.
Declaration
@
inlinable
public
func
isMultiple
(
of
other
:
Self
) -
>
Bool
Returns the quotient and remainder of this value divided by the given value.
Use this method to calculate the quotient and remainder of a division at the same time.
let
x
=
1_000_000
let
(
q
,
r
) =
x
.
quotientAndRemainder
(
dividingBy
:
933
)
// q == 1071
// r == 757
- Parameter rhs: The value to divide this value by.
Declaration
@
inlinable
public
func
quotientAndRemainder
(
dividingBy
rhs
:
Self
) -
>
(
quotient
:
Self
,
remainder
:
Self
)
Returns -1
if this value is negative and 1
if it's positive;
otherwise, 0
.
Declaration
@
inlinable
public
func
signum
() -
>
Self
Returns the result of performing a bitwise OR operation on the two given values.
A bitwise OR operation results in a value that has each bit set to 1
where one or both of its arguments have that bit set to 1
. For
example:
Declaration
public
static
func
|(
lhs
:
Self
,
rhs
:
Self
) -
>
Self
The
FixedWidthInteger
protocol adds binary bitwise operations, bit shifts, and overflow handling to the operations supported by theBinaryInteger
protocol.Use the
FixedWidthInteger
protocol as a constraint or extension point when writing operations that depend on bit shifting, performing bitwise operations, catching overflows, or having access to the maximum or minimum representable value of a type. For example, the following code provides abinaryString
property on every fixed-width integer that represents the number's binary representation, split into 8-bit chunks.The
binaryString
implementation uses the staticbitWidth
property and the right shift operator (>>
), both of which are available to any type that conforms to theFixedWidthInteger
protocol.The next example declares a generic
squared
function, which accepts an instancex
of any fixed-width integer type. The function uses themultipliedReportingOverflow(by:)
method to multiplyx
by itself and check whether the result is too large to represent in the same type.Conforming to the FixedWidthInteger Protocol
To make your own custom type conform to the
FixedWidthInteger
protocol, declare the required initializers, properties, and methods. The required methods that are suffixed withReportingOverflow
serve as the customization points for arithmetic operations. When you provide just those methods, the standard library provides default implementations for all other arithmetic methods and operators.