第三章

数字 ==

字符窜 eq


逻辑操作符:

[oracle@jhoa big]$ cat a2.pl 
if ( 2 > 1 && 3 > 2){print "ok
"};

[oracle@jhoa big]$ perl a2.pl 
ok

&& 条件同时成立, 具有短路功能, 当左边不满足条件时,就不看右边了。

[oracle@jhoa big]$ cat a2.pl 
if ( 1 > 2 && 3 > 2){print "ok
"};
[oracle@jhoa big]$ perl a2.pl 
[oracle@jhoa big]$ 

[oracle@jhoa big]$ cat a2.pl 
if ( 2 > 1 && 1 > 2){print "ok
"};
[oracle@jhoa big]$ perl a2.pl 
[oracle@jhoa big]$ 


$.  包含你的输入文件的当前行号:


Perl 引用:

[oracle@jhoa big]$ cat a3.pl 
$var = "aaaaaa";

$ref_to_var = $var;

print "1--$var is $var
";
print "2--$ref_to_var is $ref_to_var
";
print "3--$ref_to_var is $$ref_to_var
";

[oracle@jhoa big]$ perl a3.pl 
1--$var is aaaaaa
2--$ref_to_var is SCALAR(0x15310080)
3--$ref_to_var is aaaaaa