func average(of numList: [Double]) -> Double {
    if numList.count == 0 {
        return 0.0
    }
    
    var sum = 0.0
    for n in numList {
        sum += n
    }
    return sum/Double(numList.count)
}

var numbers = [3.5, 2, 1.2, 5.3]
average(of: numbers)

func averageLength(of strList: [String]) -> Double {
    if strList.count == 0 {
        return 0.0
    }
    
    var sum = 0
    for str in strList {
        sum += str.count
    }
    return Double(sum)/Double(strList.count)
}

var strings = ["apple", "banana", "casaba", "date"]
averageLength(of: strings)