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
在php中:
easter_date -获取给定年份复活节午夜的Unix时间戳
Int easter_date ([Int $year])
其他回答
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
这可能已经被提到了,但是——
PHP对八进制值的处理:
$a = 07; // 7 (as it should be)
$b = 08; // 0 (would be an error in any sensible language)
$c = 018; // 1 (again, should have been an error)
$d = 0A; // error (as it should be)
请看这里:http://bugs.php.net/bug.php?id=29676
还要注意关于这个错误的评论——Derick称其为一个特性(引用“fix”表示),而不是一个错误,他声称它会“在脚本中使用数字的所有情况下显著降低PHP的速度”——但是,为什么PHP会引发一个0A错误呢?
我认为人们可以写一整本书来讲述PHP的古怪之处……
C + + 1 xλ的:
[] (int x) { std::cout << x << std::endl; } ();
它们可能被滥用在一些奇怪的语法中:
[](){}();[]{[]{}();}();
这是完全有效的c++ 1x。
在Ruby中…
i=true
while(i)
i=false
a=2
end
puts defined?(a) // returns true
INTERCAL可能是最奇怪的语言特征的最佳汇编。我个人最喜欢的是COMEFROM语句,它(几乎)与GOTO相反。
COMEFROM is roughly the opposite of GOTO in that it can take the execution state from any arbitrary point in code to a COMEFROM statement. The point in code where the state transfer happens is usually given as a parameter to COMEFROM. Whether the transfer happens before or after the instruction at the specified transfer point depends on the language used. Depending on the language used, multiple COMEFROMs referencing the same departure point may be invalid, be non-deterministic, be executed in some sort of defined priority, or even induce parallel or otherwise concurrent execution as seen in Threaded Intercal. A simple example of a "COMEFROM x" statement is a label x (which does not need to be physically located anywhere near its corresponding COMEFROM) that acts as a "trap door". When code execution reaches the label, control gets passed to the statement following the COMEFROM. The effect of this is primarily to make debugging (and understanding the control flow of the program) extremely difficult, since there is no indication near the label that control will mysteriously jump to another point of the program.