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

在fortran中(当然是77,可能在95中也是如此),未声明的变量和以I到N开头的参数(“In”组)将是INTEGER,所有其他未声明的变量和参数将是REAL(源)。这与“在某些情况下可选的空白”相结合,导致了最著名的错误之一。

正如弗雷德·韦伯在1990年的《另类民间传说:计算机》一书中所说:

I worked at Nasa during the summer of 1963. The group I was working in was doing preliminary work on the Mission Control Center computer systems and programs. My office mate had the job of testing out an orbit computation program which had been used during the Mercury flights. Running some test data with known answers through it, he was getting answers that were close, but not accurate enough. So, he started looking for numerical problems in the algorithm, checking to make sure his tests data was really correct, etc. After a couple of weeks with no results, he came across a DO statement, in the form: DO 10 I=1.10 This statement was interpreted by the compiler (correctly) as: DO10I = 1.10 The programmer had clearly intended: DO 10 I = 1, 10 After changing the . to a , the program results were correct to the desired accuracy. Apparently, the program's answers had been "good enough" for the sub-orbital Mercury flights, so no one suspected a bug until they tried to get greater accuracy, in anticipation of later orbital and moon flights. As far as I know, this particular bug was never blamed for any actual failure of a space flight, but the other details here seem close enough that I'm sure this incident is the source of the DO story.

我认为这是一个很大的WTF,如果DO10I被作为DO10I,并且反过来,因为隐式声明被认为是类型REAL。这是个很棒的故事。

其他回答

在Java中,

Int x = 010;

这将x赋值为8。

在Java中,任何前面带0的整数都被假定为八进制。

我最喜欢的奇怪的C语言是5[“Hello World”],但因为已经发布了,我最喜欢的第二个奇怪的是Windows版本结构初始化黑客:

void someWindowsFunction() {
    BITMAPINFOHEADER header = {sizeof header};

    /* do stuff with header */
}

这条微妙的线条达到了以下效果:

Declares a BITMAPINFOHEADER structure Concisely sets the "size" member of the structure, without hardcoding a size constant (since many Window structures, including BITMAPINFOHEADER, follow the convention of specifying the size of the structure as the first member} Declares the version of the structure (since many Windows structures, including BITMAPINFOHEADER, identify their version by the declared size, following the convention that structures definitions are append-only) Clears all other members of the structure (a C standard behavior when a structure is incompletely initialized).

在ruby/python/c中,你可以像这样连接字符串:

a = "foo" "bar"
print a # => "foobar"

哈哈!

整个语言本身。虽然不完全是WTF的事情,但我从来没有遇到过一种语言在我的脑海中以一种刺耳的卡通声音播放。我以前也从来没有看过代码并想要惊呼“啊啊啊啊可爱!”

这个程序显示数字1-10并终止

HAI
CAN HAS STDIO?
IM IN YR LOOP UPPIN YR VAR TIL BOTHSAEM VAR AN 10
    VISIBLE SUM OF VAR AN 1
IM OUTTA YR LOOP
KTHXBYE

这并不是一个真正的语言特性,而是一个实现缺陷:一些早期的Fortran编译器通过使用常量池来实现常量。所有参数都是通过引用传递的。如果你调用一个函数,例如。

f(1)

编译器会将常量池中常量1的地址传递给函数。 如果您为函数中的参数赋值,则会在程序中全局地更改该值(在本例中为1)。引起了一些挠头。