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。
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
从技术上讲,WTF不是一种语言,而是一种架构。
http://www.6502.org/tutorials/6502opcodes.html#JMP
6502总成,间接JMP:
注意,间接跳转没有进位,因此: 间接跳转绝对不能使用 从最后一个字节开始的向量 一页的 例如,如果地址$3000包含$40,$30FF包含$80,$3100包含$50,JMP ($30FF)的结果将是控制权转移到$4080,而不是你想要的$5080,即6502从$30FF获取地址的低字节,从$3000获取高字节。
因此,在代码中添加一个字节可能会使间接跳转偏离目标。
其他回答
这并不奇怪或令人惊讶,但这让我总是说WTF:
语法或标识符名称的大小写敏感性。
大多数具有它的语言似乎只是因为C具有它。这样做没有什么好的理由。
在fortran中(当然是77,可能在95中也是如此),未声明的变量和以I到N开头的参数(“In”组)将是INTEGER,所有其他未声明的变量和参数将是REAL(源)。这与“在某些情况下可选的空白”相结合,导致了最著名的错误之一。
正如弗雷德·韦伯在1990年的《另类民间传说:计算机》一书中所说:
I worked at Nasa during the summer of 1963. The group I was working in was doing preliminary work on the Mission Control Center computer systems and programs. My office mate had the job of testing out an orbit computation program which had been used during the Mercury flights. Running some test data with known answers through it, he was getting answers that were close, but not accurate enough. So, he started looking for numerical problems in the algorithm, checking to make sure his tests data was really correct, etc. After a couple of weeks with no results, he came across a DO statement, in the form: DO 10 I=1.10 This statement was interpreted by the compiler (correctly) as: DO10I = 1.10 The programmer had clearly intended: DO 10 I = 1, 10 After changing the . to a , the program results were correct to the desired accuracy. Apparently, the program's answers had been "good enough" for the sub-orbital Mercury flights, so no one suspected a bug until they tried to get greater accuracy, in anticipation of later orbital and moon flights. As far as I know, this particular bug was never blamed for any actual failure of a space flight, but the other details here seem close enough that I'm sure this incident is the source of the DO story.
我认为这是一个很大的WTF,如果DO10I被作为DO10I,并且反过来,因为隐式声明被认为是类型REAL。这是个很棒的故事。
在早期版本的Visual Basic中,没有“Return”语句的函数只是“Return None”,没有任何编译器警告(或错误)。
这导致了最疯狂的调试会话,那时我必须每天处理这种语言。
这缺少了一个奇怪的特性:Python没有switch语句(尽管存在变通方法)。
Perl的$[(已弃用),这在之前关于通用Perl变量的另一篇文章中提到过,但它值得特别提到,并有更好的解释。对$[的更改仅限于当前范围。更多的信息以及如何使用它的含义;)可以在$[中找到,请访问http://www.perlmonks.org/index.pl/?node_id=480333