Swift Binary Operator "<"

Question

func min(_ numbers:Double...)->Double{

        var result:Double = 0.0
        for num in numbers{

            if num < numbers {

                result = num
            }
        }

    return result
}

Here in if num < numbers showing me error:

Binary Operator "<" can not applied to operand of double and Double

Answer 1

Probably, the error that you are mentioning is quite wrong, it should be:

Binary Operator "<" can not applied to operand of Double and [Double]

means that you are trying to compare between a double and an array of doubles (numbers).

What are you trying to implement should be:

func min(_ numbers: Double...) -> Double? {
    guard var result = numbers.first else {
        return nil
    }

    for num in numbers {
        if result > num {
            result = num
        }
    }

    return result
}

Usage:

if let minResult = min(2.1, 61.2, 33.6, 9.3, 4.2, 6.1, 6.1, 6.1, 3.4) {
    print(minResult) // 2.1
}

let nilResult = min() // nil

Note that min should returns an optional value, because -as mentioned in the code snippet- a function with variadic parameter is able to take 0 parameters without using the label.

Also:

I would recommend to use min() array method, as follows:

func min(_ numbers: Double...) -> Double? {
    return numbers.min()
}

The output should be the same...