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import Foundation
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# Bitwise Operators
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var a: UInt8 = 0b00001111
var b: UInt8 = 0b11110000
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NOT
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print(~a == b) // true
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AND
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print(a & b == 0) // true
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OR
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print(a | b == 0b11111111) // true
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XOR
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print(a ^ b == a | b) // true
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Shifts (unsigned)
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print(a << 1 == 0b00011110)
print(a >> 1 == 0b00000111)
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# Overflow Operators
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Normally Swift will error when and over/under
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flow occurs.
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var num = UInt8.max
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error: arithmetic operation results in an overflow
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/* var zero = num + 1 */
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But prefixing the operator with "&" tells Swift
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that you want this behavior.
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var zero = num &+ 1
print(zero == 0) // true
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# Operator Functions
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Operator overloading is a supported language feature,
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but it isn't a best practice in most cases.
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struct Trip {
var distance = 0.0, duration = 0.0
}
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Defines an 'infix' + operator that handles two args.
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func + (left: Trip, right: Trip) -> Trip {
return Trip(distance: left.distance + right.distance,
duration: left.duration + right.duration)
}
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Defines a 'prefix' - operator that handles a single arg.
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prefix func - (trip: Trip) -> Trip {
return Trip(distance: trip.distance * -1.0, duration: trip.duration * -1.0)
}
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Compound assignments are also supported.
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func += (inout left: Trip, right: Trip) {
left = left + right
}
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As well as assignment expressions.
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prefix func ++ (inout trip: Trip) -> Trip {
trip += Trip(distance: 1.0, duration: 1.0)
return trip
}
var tripA = Trip(distance: 100.0, duration: 2.0)
var tripB = Trip(distance: 250.0, duration: 5.0)
var combined = tripA + tripB
print("Went \(combined.distance) in \(combined.duration)") // Went 350.0 in 7.0
var disaster = -tripA
print("Went \(disaster.distance) in \(disaster.duration)") // Went -100.0 in -2.0
tripA += tripB
tripA += tripB
print("Went \(tripA.distance) in \(tripA.duration)") // Went 600.0 in 12.0
++tripA
print("Went \(tripA.distance) in \(tripA.duration)") // Went 601.0 in 13.0
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You can also define your own bananas custom operators with
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/ = - + * % < > ! & | ^ . ~
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postfix operator -=- {}
postfix func -=- (inout trip: Trip) -> Trip {
trip = Trip(distance: Double(Int(trip.distance) * random()),
duration: Double(Int(trip.duration) * random()))
return trip
}
tripA-=-
print("Went \(tripA.distance) in \(tripA.duration)") // Went 602222301.0 in 1311110111.0
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