在你看来,你遇到过的最令人惊讶、最怪异、最奇怪或最“WTF”的语言特性是什么?

请每个回答只回答一个特征。


当前回答

Perl中的字符串数学非常奇怪。

$ perl -E '$string = "a"; $string++; say $string'
b

$ perl -E '$string = "abc"; $string++; say $string'
abd

$ perl -E '$string = "money"; $string++; say $string'
monez

$ perl -E '$string = "money"; $string--; say $string'
-1

其他回答

Haskell's use of Maybe and Just. Maybe a is a type constructor that returns a type of Just a, but Maybe Int won't accept just an Int, it requires it to be a Just Int or Nothing. So in essence in haskell parlance Just Int is about as much of an Int as an apple is an orange. The only connection is that Just 5 returns a type of Maybe Interger, which can be constructed with the function Just and an Integer argument. This makes sense but is about as hard to explain as it can theoretically be, which is the purpose of haskell right? So is Just really JustKindaLikeButNotAtAll yea sorta, and is Maybe really a KindaLooksLikeOrIsNothing, yea sorta again.

-- Create a function that returns a Maybe Int, and return a 5, which know is definitly Int'able
>  let x :: Maybe Int; x = 5;
<interactive>:1:24:
    No instance for (Num (Maybe Int))
      arising from the literal `5' at <interactive>:1:24
    Possible fix: add an instance declaration for (Num (Maybe Int))
    In the expression: 5
    In the definition of `x': x = 5

>  Just 5  
Just 5
it :: Maybe Integer

    -- Create a function x which takes an Int
>  let x :: Int -> Int; x _ = 0;
x :: Int -> Int
-- Try to give it a Just Int
>  x $ Just 5                   

<interactive>:1:4:
    Couldn't match expected type `Int' against inferred type `Maybe t'
    In the second argument of `($)', namely `Just 5'
    In the expression: x $ Just 5
    In the definition of `it': it = x $ Just 5

祝你好运读到这篇文章,我希望它是正确的。

JavaScript八进制转换“特性”是一个很好的了解:

parseInt('06') // 6
parseInt('07') // 7
parseInt('08') // 0
parseInt('09') // 0
parseInt('10') // 10

详情请点击这里。

VBScript的日期/时间文字(为什么这个仍然如此罕见?):

mydate = #1/2/2010 5:23 PM#

If mydate > #1/1/2010 17:00# Then ' ...

编辑:日期文字是相对的(那么它们在技术上是文字吗?):

mydate = #Jan 3# ' Jan 3 of the current year

VB。NET,因为它是编译的,所以不支持相对日期文字。只支持日期或时间字面量,但缺失的时间或日期被假定为零。

编辑[2]:当然,有一些奇怪的极端情况会出现相对日期……

mydate = #Feb 29# ' executed on 2010-01-05, yields 2/1/2029

我喜欢在C中插入八进制值:

int values[8] = { 123, 154, 103, 310, 046, 806, 002, 970 };

在JavaScript(和Java)中,你可以转义这样有趣的字符:

var mystring = "hello \"world\"";

如果你想把回车放到字符串中,那是不可能的。你必须像这样使用\n:

var mystring = "hello, \nworld";

这是正常的,也是意料之中的——至少对于一种编程语言来说。奇怪的是你也可以像这样转义一个实际的回车:

var mystring = "hello, \
world";