#!/usr/bin/perl -w
my @names = qw /petty ali amily alice  /;
print "@names\n";
change(@names);
print @names;

 
sub change 
{
    my(@source) = @_;
    print "\@_:@_\n";
    print "\$_:$_\n";
#    $_[1]="hello world";
#    @_[1]="hello world";
}

被注释掉的两行如果，如果调用@_[1]=...，就会出现Scalar value @_[1] better written as $_[1] at ./a.pl line 13.
如果调用$_[1]=...，之前调用print "\$_:$_\n"会有提示Use of uninitialized value $_ in concatenation (.) or string at ./a.pl line 11.，$_的值输出是空。但是结果确又确实是修改了，不知道这个是如何处理的。