October 2022
Beginner to intermediate
390 pages
7h 5m
Chinese
Content preview from Perl语言入门（第8版）
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34
｜
第
2
章
所谓的编译指令（
pragma
），是指告诉
Perl
编译器该如何行动的指令。
和数字一样，字符串也可以写作直接量。这其实就是在
Perl
程序中书写字符串的方
式：单引号圈引的字符串直接量以及双引号圈引的字符串直接量。
单引号内的字符串直接量
单引号内的字符串直接量就是写在一对单引号（
'
）内的一串字符。前后两个单引号
并不是字符串的内容，只是边界，用于让
Perl
判断字符串的开头与结尾：
'fred' #
总共
4
个字符：
f
、
r
、
e
和
d
'barney' #
总共
6
个字符
'' #
空字符串（没有字符）
34
｜
第
2
章
和数字一样，字符串也可以写作直接量。这其实就是在
Perl
程序中书写字符串的方
式：单引号圈引的字符串以及双引号圈引的字符串。
单引号内的字符串直接量
单引号内的字符串直接量就是写在一对单引号（
'
）内的一串字符。前后两个单引号
只是边界，并不是字符串的内容，用于让
Perl
判断字符串的开头与结尾：
'fred' #
总共
4
个字符：
f
、
r
、
e
和
d
'barney' #
总共
6
个字符
'' #
空字符串（没有字符）
'
⅚
∞
☃☠
' #
某些“宽”
Unicode
字符
除了单引号和反斜线字符外，单引号内所有字符都代表它们自己。如果要在字符串中
使用单引号和反斜线，需要添加一个反斜线用作转义：
'Don\'t let an apostrophe end this string prematurely!'
'the last character ...
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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.