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

下面的c#代码抛出NullReferenceException而不是打印1:

    static void SomeMethod(string format, params object[] args)
    {
        Console.WriteLine(args.Length);
    }

    static void Main(string[] args)
    {
        SomeMethod("blabla", null, "Ok here"); // print 2
        SomeMethod("blabla", null); // exception
    }

其他回答

我一直在想为什么最简单的程序是:

class HelloWorldApp {
    public static void main(String[] args) {
        System.out.println("Hello World!");
    }
}

然而它可以是:

print "Hello World!"

也许这是为了吓唬计算机科学专业的学生……

c# yield语句,并不奇怪,但非常有用。

http://msdn.microsoft.com/en-us/library/9k7k7cf0 (VS.80) . aspx

在javaScript中,NaN是一个全局变量。

PHP对字符串中数值的处理。详见之前对另一个问题的回答,但简而言之:

"01a4" != "001a4"

如果你有两个包含不同数量字符的字符串,它们不能被认为是相等的。前导零很重要,因为它们是字符串而不是数字。

"01e4" == "001e4"

PHP doesn’t like strings. It’s looking for any excuse it can find to treat your values as numbers. Change the hexadecimal characters in those strings slightly and suddenly PHP decides that these aren’t strings any more, they are numbers in scientific notation (PHP doesn’t care that you used quotes) and they are equivalent because leading zeros are ignored for numbers. To reinforce this point you will find that PHP also evaluates "01e4" == "10000" as true because these are numbers with equivalent values. This is documented behaviour, it’s just not very sensible.

NSIS (Nullsoft Scriptable安装系统)有StrCmp指令:

StrCmp str1 str2 jump_if_equal [jump_if_not_equal] 比较str1和str2(不区分大小写)。如果str1和str2相等,则Gotos jump_if_equal,否则Gotos jump_if_not_equal。 StrCmp $0“一个字符串”0 +3 DetailPrint '$$0 == "a string"' 转到+ 2 DetailPrint '$$0 != "a string"'

锦上添花:jump_if_equal和jump_if_not_equal也可以是负数。但我猜你们已经从正数前面的+符号中算出来了。我不记得这是强制性的,还是只是一个可怕的惯例。

这基本上结合了最差的BASIC和最差的Assembler。