옵셔널 바인딩 연습

var number: Int? = 7
var hello: String? = "안녕하세요"
var name: String? = "조소야"
var newNum: Double? = 5.5

print(number)
print(hello)
print(name)
print(newNum)

if let num = number {
    print(num)
}else{
    print("number = nil")
}
if let h = hello {
    print(h)
}
if let n = name{
    print(n)
}
if let d = newNum {
    print(d)
}


func doPrint(num: Int?){ // guard 는 func 안에 있어야한다.
    guard let n = num else { return }
    print(n)
}

doPrint(num: number)


func doHello(hello: String?){
    guard let hi = hello else {return}
    print(hi)
}

doHello(hello: hello)