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

JavaScript真值表:

''        ==   '0'           // false
0         ==   ''            // true
0         ==   '0'           // true
false     ==   'false'       // false
false     ==   '0'           // true
false     ==   undefined     // false
false     ==   null          // false
null      ==   undefined     // true
" \t\r\n" ==   0             // true

资料来源:Doug Crockford

其他回答

在PHP中,必须显式地引用全局变量,并显式地使用这个->作为类变量。使重构变得有趣。如果不找到所有使用点,就不能将变量/参数提升为全局变量或类成员。

Powerbasic (www.powerbasic.com)包含编译器指令:

# BLOAT {bloatsize}

这将使编译后的可执行文件的大小增加<bloatsize>字节。这是放在编译器中,以防创建可执行文件的人不喜欢生成的可执行文件的小尺寸。它使EXE看起来更大,以与臃肿的编程语言竞争:)

在流行性腮腺炎中,你可以有一个带偏移的GOTO。如果你有(我的腮腺炎已经生锈了…)

some_label if x=1 do_something
           else  do_something_else

然后是代码

           goto some_label+1

将跳转到ELSE语句…

C# has a feature called "extension methods", which are roughly analogous to Ruby mix-ins - Essentially, you can add a method to any pre-existing class definition (for instance, you oould add "reverse()" to String if you were so inclined). That alone is fine- The "Weird" part is that you can add these extension methods, with a method body and everything, to an interface. On the one hand, this can be handy as a way to add a single method to a whole swath of classes which aren't part of the same inheritance tree. On the other, you're adding fleshed out methods to interfaces, essentially breaking the very definition of an interface.

在javaScript中,NaN是一个全局变量。