perl sort <=> and cmp

发布时间：2020-12-16 00:39:25 所属栏目：大数据来源：网络整理

导读：Perl has two operators = and cmp , which are very useful when wishing to sort arrays. $a = $b returns -1 if $a is numerically lesser than $b ,1 if it's greater,and zero if they are equal. cmp does the same for string comparison. For instan

Perl has two operators <=> and cmp,

which are very useful when wishing to sort arrays. $a <=> $b returns -1 if $a is numerically lesser than $b,1 if it's greater,and zero if they are equal.

cmp does the same for string comparison. For instance the previous example could be re-written as:

 [liuguiyou@localhost perl]$ cat sort.pl
 #!/usr/bin/perl

 use strict;
 use warnings;

 my @array = (100,5,8,92,-7,34,29,58,10,24);

 my @sorted_array = sort { $a <=> $b } @array;

 print join("<",@sorted_array),"n";

 [liuguiyou@localhost perl]$ ./sort.pl
 -7<5<8<8<10<24<29<34<58<92<100

Much more civil,isn't it? The following example,sorts an array of strings in reverse:

 [liuguiyou@localhost perl]$ cat sort_chara.pl #!/usr/bin/perl  use strict; use warnings;  my @input = ( ??? "Hello World!",??? "You is all I need.",??? "To be or not to be",??? "There's more than one way to do it.",??? "Absolutely Fabulous",??? "Ci vis pacem,para belum",??? "Give me liberty or give me death.",??? "Linux - Because software problems should not cost money",);  # Do a case-insensitive sort my @sorted = sort { lc($a) cmp lc($b); } @input;  print join("n",@sorted),"n";   [liuguiyou@localhost perl]$ ./sort_chara.pl Absolutely Fabulous Ci vis pacem,para belum Give me liberty or give me death. Hello World! Linux - Because software problems should not cost money There's more than one way to do it. To be or not to be You is all I need.

（编辑：李大同）

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perl sort &lt;=&gt; and cmp

perl sort <=> and cmp