因为它不是 Perl.你从哪里学的那个语法?它有很多问题.

Because it's not Perl. Where did you learn that syntax? So much is wrong with it.

1. $param = "" 给 $param 分配一个空字符串，这不是你想要的.

1. $param = "" assigns an empty string to $param, that's not what you want.

null 拼写为 undef 在 Perl 中.

null is spelled undef in Perl.

要比较字符串，请使用 eq 运算符.

To compare strings, use the eq operator.

您必须引用字符串:打印无参数"

更容易:

#!/usr/bin/perl
if (@ARGV) {
    print 'have parameters';
} else {
    print q{don't have parameters};
}