整数溢出在 Swift 中给出 EXC_BAD_INSTRUCTION [英] Integer overflow gives EXC_BAD_INSTRUCTION in Swift

问题描述

在使用 Swift 时，我注意到当 64 位整数溢出时，我收到以下错误:

While messing around with Swift, I noticed that when the 64 bit integer overflows, I get the following error:

file:///Users/user/Documents/playground/MyPlayground.playground/:错误:Playground 执行中止:执行被中断，原因:EXC_BAD_INSTRUCTION(代码=EXC_I386_INVOP，子代码=0x0).

file:///Users/user/Documents/playground/MyPlayground.playground/: error: Playground execution aborted: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0).

func fibonacci(which: Int) -> (fibOf: Int, isEqualTo: Int) {
    var i = 1, j = 1

    for var k = 2; k < which; k += 1 {
        let tmp = i + j // this line is highlighted when error occurs
        j = i
        i = tmp
    }

    return (which, i)
}

print (fibonacci(92))
print (fibonacci(93)) // this triggers an error

第一次调用，即以 92 作为参数，将运行良好.然而，当提供 93 值时，我得到了不相关的 EXC_BAD_INSTRUCTION 错误.这是错误还是什么?通常我希望它会溢出.

The first call, i.e. with 92 as argument, will run fine. When supplying the 93 value however, I get the irrelevant EXC_BAD_INSTRUCTION error. Is this a bug or what? Normally I'd expect it to overflow.

推荐答案

这是预期的行为.如果要溢出，则需要使用溢出运算符.

It is expected behaviour. If you want to overflow, you need to use overflow operators.

• 溢出加法(&+)
• 溢出减法(&-)
• 溢出乘法(&*)

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