Currently focused on structures and algorithms and I came across this one.
import Foundation
let numbers = [1, 3, 56, 66, 68, 80, 99, 105, 450]
func naiveContains(_ value: Int, in array: [Int]) -> Bool {
guard !array.isEmpty else { return false }
let midleIndex = array.count / 2
if value <= array[midleIndex] {
for index in 0...midleIndex {
if array[index] == value {
return true
}
}
} else {
for index in midleIndex..<array.count {
if array[index] == value {
return true
}
}
}
return false
}
The exact location of my question is the guard statement:
guard !array.isEmpty else { return false }
I am not sure why the guard statement requires, ! in !array.isEmpty
I only need help in understanding why the exclamation mark needs to be placed before the array parameter.
Thank you!
The algorithm requires the array to be not empty. ! means not. So !array.isEmpty means is not empty.
The meaning of guard ...
is like if not ...
So guard !array.isEmpty
means if not not array is empty
, which in turn is equivalent with if array.isEmpty {return false}
I can see it is confusing!