【Perl读书笔记】defined函数

读 《C程序员精通Perl》http://book.douban.com/subject/1232075/   2.4.4节 笔记

#!/usr/bin/perluse strict;use warnings;my $name = "calf_man";my $value;if (defined($name)) {        print "The name is defined as $name\n";}if (not defined($value)) {        print "The value is not defined.\n";}#$name = undef; undef($name);#undef #name;if (not defined($name)) {        print "The name is not defined.\n";}

运行结果：

[root@localhost perl_practice]# ./define.pl   
The name is defined as calf_man
The value is not defined.
The name is not defined.
[root@localhost perl_practice]#