Question

How to implement the power function in Swift

Answer 1

import Foundation

func myPow(base: Double, exponent: Int) -> Double {
    var result: Double = 1.0
    var baseVar = base
    var expVar = exponent

    while expVar > 0 {
        if (expVar & 1) == 1 {
            result *= baseVar
        }
        expVar >>= 1
        baseVar *= baseVar
    }

    return result
}

print(myPow(base:2.0, exponent:3))  // 8
print(myPow(base:3.0, exponent:3))  // 27
print(myPow(base:3.0, exponent:2))  // 9
print(myPow(base:2.0, exponent:2))  // 4
print(myPow(base:5.0, exponent:2))  // 25
print(myPow(base:-2.0, exponent:4)) // 16



/*
run:

8.0
27.0
9.0
4.0
25.0
16.0

*/

 

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