Swift : Program for addition of 2 numbers using closure

Question

let fileName = ProcessInfo.processInfo.environment[\"OUTPUT_PATH\"]!
FileManager.default.createFile(atPath: fileName, contents: nil, attributes: nil)
let fileHandle = Fi         


        

Answer 1

Closures are really simple in Swift. Here is an example Closure for adding two numbers:

let closure:((Int, Int) -> Int) = { (number1, number2) in
    return number1 + number2
}

Just like with normal variables you set the type of a closure after a colon. In this case it's:

((Int, Int) -> Int)

which means: Take two Ints as parameters and return a Int.

Usage:

let firstNumber = 5
let secondNumber = 6

let additionResult = closure(firstNumber, secondNumber)
//additionResult is 11

In your specific use case:

let closure:((Int, Int) -> Int) = { (number1, number2) in
    return number1 + number2
}

let fileName = ProcessInfo.processInfo.environment["OUTPUT_PATH"]!
FileManager.default.createFile(atPath: fileName, contents: nil, attributes: nil)
let fileHandle = FileHandle(forWritingAtPath: fileName)!

guard let number1 = Int((readLine()?.trimmingCharacters(in: .whitespacesAndNewlines))!)
else { fatalError("Bad input") }

guard let number2 = Int((readLine()?.trimmingCharacters(in: .whitespacesAndNewlines))!)
else { fatalError("Bad input") }

let res = closure(number1, number2)

fileHandle.write(String(res).data(using: .utf8)!)
fileHandle.write("\n".data(using: .utf8)!)