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
｜
39
非十进制数字的转换
如果有一个以其他进制表示的数字字符串，我们可以用
hex()
或
oct()
函数将字符
串转换为对应的数字。并且，如果字符串以特定的十六进制或二进制前缀字符开头
的话，
oct()
函数能聪明地根据该进制进行转换，不过十六进制字符串必须以
0x
开
头，请参考具体例子：
hex('DEADBEEF') #
即十进制数字
3_735_928_559
hex('OxDEADBEEF') #
也是十进制数字
3_735_928_559
oct('0377') #
十进制数字
255
oct('377') #
十进制数字
255
oct('0xDEADBEEF') #
是十进制数字
3_735_928_559
，因为看到了开头的
0x
oct('0b1101') #
是十进制数字
13
，因为看到了开头的
0b
oct("0b$bits") #
将变量
$bits
中的值当作二进制数字转换为十进制数字
那些写成字符串形式的数字是给人读的，计算机并不关心你原来怎么写。你用十进制
还是十六进制写，
Perl
都无所谓。只要我们自己弄清楚数字大小，
Perl
会自动将其转
换为内部的存储格式。
再提醒一下，
Perl
在自动转换时总是把字符串转换成十进制数，而以上这两个函数只
接受字符串作为参数，所以如果你直接写数字直接量的话，往往会弄错结果。因为
Perl
会先把参数转换为字符串，然后再转换为其他进制的数字，而这个数字已经和原
来的直接量数字不相等了： ...
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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.