您当前的位置: 大家好，我写了一段程序，但是发现出现语法错误，请大家指点一下。谢谢！具体源码如下：
- Perl code
#!/usr/bin/perl
use 5.010;
use strict;
use diagnostics;
use feature 'state';
sub greet
{
state $name;
if(!defined($name)) #这里判断静态变量$name是否已经定义
{
$name=$_;
print "Hi ", $_, "! ", $name, " is also here ! \n";
}
else
{
print "Hi ", $_, "! ", $name, " is also here ! \n";
}
}
greet("Fred");
greet("Barney");
系统提示：
Use of uninitialized value $_ in print at ./Ex4_4 line 13 (#1)
(W uninitialized) An undefined value was used as if it were already
defined. It was interpreted as a "" or a 0, but maybe it was a mistake.
To suppress this warning assign a defined value to your variables.
请问这个原因是什么？
------解决方案--------------------
你把 @_ 和 $_ 弄混了
- Perl code
state $name; $_=shift; #加上这行就可以了 if(!defined($name))
------解决方案--------------------
为啥要把$_给变量name呢?
$_的用法你知道吗?