Re^2: adding to hash/writing to file errors

Okay, here is the revised version, now i get this error when it is compiling:
Global symbol "%logins" requires explicit package name at ./maybe.pl line 62. Execution of ./maybe.pl aborted due to compilation errors.

#    AGTS-CLI(Andrew's GTK Time System-Command Line version)
#    Copyright (C) 2008  Andrew Harris
#
#    This program is free software: you can redistribute it and/or mod
+ify
#    it under the terms of the GNU General Public License as published
+ by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, email andrew2325@gmail.com!
#    Contributors:  Kelly Royal <netdaemon862@gmail.com>
#!/usr/bin/perl
use strict;
use warnings;
my $time = localtime;
sub verify {
    my $username = shift;
    my %logins = ("aharris" => "1234", "kroyal" => "5678");
    if (exists $logins{$username}) {
        login($username, %logins);
    }
    else {
        print "$username does not exist in our database.\n";
    }
}

sub login {
    my %logins = shift;
    my $username = shift;
    print "Enter your password: ";
    chomp(my $pass = <STDIN>);
    if ($pass <=> $logins{$username}) {
        greeting($username);
    }
    else {
        print "Incorrect password!\n";
    }
}

sub greeting {
    my $username = shift;
    print "Welcome $username.\n";
    print "Current time is $time\n\n\n";
}

sub admin {
    print "Administrative Tools\n";
    print "1. Add user\n";
    print "2. Remove user\n";
    print "Enter selection: ";
    chomp(my $selection = <STDIN>);
    if ($selection == "1") {
        print "Enter new user name: ";
        chomp(my $newname = <STDIN>);
        print "Enter password for $newname: ";
        chomp(my $newpass = <STDIN>);
        $logins{$newname} = $newpass;
        print "User added.\n";
    }
}
while (1) {
print "Welcome, Main Menu\n";
print "1. Log in\n";
print "2. Log out\n";
print "3. Administration\n";
print "Enter selection: ";
my $selection = <STDIN>;
if ($selection == "1") {
    print "Enter your user name to log in: ";
    chomp(my $username = <STDIN>);
    verify($username);
    open(MYLOGINFILE, ">>login.txt");
    print MYLOGINFILE "$username:$time\n";
    close(MYLOGINFILE);
}
elsif ($selection == "2") {
    print "Enter your user name to log out: ";
    chomp(my $username = <STDIN>);
    verify($username);
    open(MYLOGOUTFILE, ">>login.txt");
    print MYLOGOUTFILE "$username:$time\n";
    close(MYLOGOUTFILE);
}
elsif ($selection == "3") {
    admin;    
}
}
[download]

When I remove use strict; use warnings;, it runs, but it doesn't add the users/passwords to the hash..

Comment on Re^2: adding to hash/writing to file errors Download Code

Replies are listed 'Best First'.
Re^3: adding to hash/writing to file errors by toolic (Bishop) on May 05, 2008 at 14:48 UTC
`use strict;` requires that you declare all variables using my in all scopes. The variable `$username` is used in your "login" sub, but it is not declared there, nor is it declared as a global variable. Since your call to "login" is: `login($username, %logins);` [download] I believe you might want: `sub login { my $username = shift; my %logins = shift;` [download] You only declare your `$time` variable in your "greeting" sub, but you use it in the "while" loop.	[reply] [d/l] [select]
Re^4: adding to hash/writing to file errors by andrew2325 (Initiate) on May 05, 2008 at 16:02 UTC
Okay, I got rid of the errors it was returning, now the only problem is it won't add users, and only one of the default users works! I haven't a clue as to why it is doing this. Any suggestions would be appreciated.	[reply]
Re^5: adding to hash/writing to file errors by toolic (Bishop) on May 05, 2008 at 17:08 UTC
One of the quickest ways to debug Perl code is to start placing `print` statements near where you are having trouble. For looking at the contents of array and hash variables, `use Data::Dumper;`. For example, to inspect values passed into a sub: `print Dumper(\@_);` [download] Taking another pass through your code, I see a couple of unusual things: `my %logins = shift;` [download] Inside a sub, shift will remove a single element from the `@_` array, not an entire hash as you may expect. See for yourself with: `print Dumper(\%logins);` [download] You may want to consider passing hashes by reference (see perlreftut). Another oddity is: `if ( $pass <=> $logins{$username} ) {` [download] What are you trying to accomplish there? Another recommendation is to take advantage of your modular approach by testing your individual subs.	[reply] [d/l] [select]
Re^3: adding to hash/writing to file errors by apl (Monsignor) on May 05, 2008 at 15:16 UTC
first i had use strict; use warnings; in there, but it wouldn't run the script. just gave a warning about line 83. then i removed it to see if it would work without the debugging. Did you consider fixing the bug that caused the warning on line 83? `use warnings; use strict;` aren't debugging aids. They help reveal badly constructed Perl. You debug your program after it compiles cleanly.	[reply] [d/l]
Re^4: adding to hash/writing to file errors by andrew2325 (Initiate) on May 05, 2008 at 16:24 UTC
There are no more warnings. The only problem I have now is adding users, and it will only log in for one of the default users(aharris). What program should I use to debug it? When I run it, I get: 1. Log in 2. Log out 3. Administration Enter selection: 1 Enter your user name to log in: aharris Odd number of elements in hash assignment at ./maybe.pl line 23, <STDIN> line 2. Odd number of elements in hash assignment at ./maybe.pl line 33, <STDIN> line 2. Enter your password: 1234 Use of uninitialized value $logins{"aharris"} in numeric comparison (<=>) at ./maybe.pl line 37, <STDIN> line 3. Welcome aharris. Current time is Mon May 5 11:44:51 2008 ?	[reply]
Re^5: adding to hash/writing to file errors by apl (Monsignor) on May 05, 2008 at 16:48 UTC
Take a look at the Perl Debugger tutorial.	[reply]
Re^5: adding to hash/writing to file errors by starbolin (Hermit) on May 05, 2008 at 16:57 UTC
Starting your script like: perl -d scriptname.pl will bring it up in the perl debugger. Read perldebug. You may also want to dump your data structures at opportune moments with Data::Dumper. Your code is well formatted and except for the while() loop surrounding a bunch of subroutine definitions ( the subroutine definitions should be outside the execution path ) otherwise the code is very readable. The parameter passing is incorrect however. Subroutine calls like some_sub( %hash ) are usually not correct as perl passes your hash structure as a flat list which then becomes a local copy in the subroutine. What you probably should be doing is passing a reference to the hash. See: perlreftut. This is why your data structure is not getting updated as your routines only modify their local copy of the structure. s//----->\t/;$~="JAPH";s//\r<$~~/;{s\|~$~-\|-~$~\|\|\|s \|-$~~\|$~~-\|\|\|s,<$~~,<~$~,,s,~$~>,$~~>,, $\|=1,select$,,$,,$,,1e-1;print;redo}	[reply] [d/l]