CODEWITHSUNDEEP
arraysswiftswift2
Rahul
Rahul

Reputation: 2100

Generic type array do not take empty array as input

import Foundation


func insertionSort<T where T: Comparable>(var items:[T])-> [T] {

    for (index, _) in items.enumerate().dropFirst() {
        var j = index

        while ((j > 0) && (items[j] < items[j-1])) {
            swap(&items[j], &items[j-1])
            j = j-1
        }
    }
    return items
}


// Test the function
insertionSort([]) // Generic type array is not taking empty array

When I am trying to call insertionSort with empty array, I get 

Cannot invoke 'insertionSort' with an argument list of type '([_])'

I am not able to figure out how to fix this.

Upvotes: 2

Views: 424

Answers (1)

OOPer
OOPer

Reputation: 47896

To call generic functions in Swift, Swift needs to be able to infer the generic parameters.

One way giving the type information to Swift, is using an intermediate variable. (Like noted in Lu_'s comment.)

let arr: [Int] = []
let result = insertionSort(arr)

Another way is using as.

let result = insertionSort([] as [Int])

(Remember, var parameter does not modify the actual argument. It just makes a mutable copy, but does not write it back to the original argument. Swift 3 removed var parameters, as it's so confusing. You may need to assign the return value of the function to a variable.)

Upvotes: 2

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