热爱开源，热爱linux
分类： LINUX
2011-01-03 11:01:31
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,-7,34,29,58,8,10,24);
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.
下面有一个例子计算几个不同的学生的平均成绩，例如ceagle 计算他4门课的平均成绩
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