我是perl的新手。我试图通过编写一些程序来理解它。perl 中的作用域让我很难过。
我写了以下内容:
use 5.16.3;
use strict;
use Getopt::Long;
Getopt::Long::Configure(qw(bundling no_getopt_compat));
&ArgParser;
our ($sqluser,$sqlpass);
$sqluser="root";
$sqlpass="mypassword";
sub ArgParser {
print "Username is ".$sqluser." Password is ".$sqlpass."\n";
my $crt='';
my $delete='';
GetOptions ('create|c=s' => \$crt,
'delete|d=s' => \$delete
);
if ($crt) {
&DatabaseExec("create",$crt);
} elsif ($delete) {
&DatabaseExec("delete",$delete);
} else {
print "No options chosen\n";
}
}
sub DatabaseExec {
use DBI;
my $dbname=$_[1];
print "Username is ".$sqluser." Password is ".$sqlpass."\n";
my $dbh = DBI->connect("dbi:mysql:", $sqluser,$sqlpass);
my $comand=$_[0];
if ($_[0] eq "create") {
my $db_com="create database ".$dbname;
print 1 == $dbh->do($db_com) ? "Database created\n":"An error occured while creating database. Maybe it exists?\n";
#print "Executing: ".$db_com."\n";
} elsif ($_[0] eq "delete") {
my $db_com="DROP DATABASE ".$dbname;
#print "Executing: ".$db_com."\n";
print 1 == $dbh->do($db_com) ? "Database deleted\n":"An error occured while creating database. Maybe it exists?\n";
}
}
我的理解是,我们会将这些声明为全局变量,以供主代码和子程序使用。然而,这给出了以下输出:
#~/perlscripts/dbtest.pl -c hellos
Use of uninitialized value $sqluser in concatenation (.) or string at /root/perlscripts/dbtest.pl line 20.
Use of uninitialized value $sqlpass in concatenation (.) or string at /root/perlscripts/dbtest.pl line 20.
Username is Password is
Use of uninitialized value $sqluser in concatenation (.) or string at /root/perlscripts/dbtest.pl line 44.
Use of uninitialized value $sqlpass in concatenation (.) or string at /root/perlscripts/dbtest.pl line 44.
Username is Password is
DBI connect('','',...) failed: Access denied for user 'root'@'localhost' (using password: NO) at /root/perlscripts/dbtest.pl line 45.
Can't call method "do" on an undefined value at /root/perlscripts/dbtest.pl line 50.
我不想将这些作为参数传递给 sub,而是将它们用作全局变量。有人可以帮我确定我对范围界定的误解吗?