SWIFT 中的 continue、break、fall-through、 throw 和 return 之间有什么区别 [关闭]

SWIFT 中的 continue、break、fall-through、throw 和 return 是用于控制程序流程的关键字，它们在使用上有一些区别。

swift
for i in 1...5 {
    if i == 3 {
        continue
    }
    print(i)
}

1
2
4
5

swift
for i in 1...5 {
    if i == 3 {
        break
    }
    print(i)
}

1
2

swift
let grade = "A"
switch grade {
case "A":
    print("Excellent")
    fallthrough
case "B":
    print("Good")
default:
    print("Pass")
}

Excellent
Good

swift
enum CustomError: Error {
    case invalidInput
    case outOfRange
}
func checkNumber(_ num: Int) throws {
    if num < 0 {
        throw CustomError.invalidInput
    } else if num > 100 {
        throw CustomError.outOfRange
    } else {
        print("Number is valid")
    }
}
do {
    try checkNumber(50)
} catch CustomError.invalidInput {
    print("Invalid input")
} catch CustomError.outOfRange {
    print("Out of range")
} catch {
    print("Unknown error")
}

Number is valid

swift
func divide(_ a: Int, by b: Int) -> Int {
    if b == 0 {
        return -1
    }
    return a / b
}
let result = divide(10, by: 2)
print(result) // 输出：5