August 2018
Beginner to intermediate
382 pages
7h 14m
Chinese
Content preview from Perl语言入门
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标量数据
｜
33
当取模操作符两边有一边（或两边）是负数的时候，在不同
Perl
版本中的计算结果可
能会有所出入。因为人们对负数进位的方式一直存在争论，所以
Perl
依赖的底层库
的行为飘乎不定，造成负数取模运算的结果不总是一致的。比如
-10 % 3
，如果按距
离
-12
来说，还差两步，答案是
2
；如果按距离
-9
来说，又多了一步，所以余
-1
。
哪种结果才算正确？最好还是避免这种意义不明的计算。
Perl
还提供一种类似
FORTRAN
语言的乘幂（
exponentiation
）操作符，写作两个星
号
**
，比如
2**3
，表示
2
的
3
次方，结果是
8
。除了这里介绍的，还有一些数字操
作符，后续我们会在讨论相应例子时具体介绍。
字符串
字符串就是一连串的字符序列，比如
hello
或者
because people disagree about rounding numbers. For -10 % 3, is the remainder 2
because it’s two places above -12 or -1 because it’s one place from -9? It’s best to avoid
finding out accidentally.
Additionally, Perl provides the FORTRAN-like exponentiation operator, represented
by the double asterisk. ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.