Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question: 


my @shifts = qw( 5:00am 5:30am 6:00am 6:30am 7:00am 7:30am 8:00am 8:30
+am 9:00am );


print " enter time to schedul \n";

read $time;

open my $fh, '+<', 'students.dat' or die "open failed: $!";
flock $fh, LOCK_EX or die "flock failed: $!";

my $found = 0;
while (<$fh>) {

   $found = 1 if index($_, $time)== 0;
}

print $fh $locationNumber ,"\t" , $studentNumber ,"\t" , $time ,"\n" u
+nless $found;

close $fh;


}


students.dat
------------
name     Number  time
Sam      04      5:00am
Eddi     23      5:30am

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What I am trying to do is ,if I find a person that already schedul , then I will only allow to sechdul him again an hour later, so if I have somone schedul at 5:00am , I can only schedul him at 6:00am but not 5:30am . Can anyone advice ? thanks

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Re: updating file
by jdporter (Paladin) on Apr 08, 2004 at 16:48 UTC

    Ooh, I just love the smell of homework.

    First thing you need to do is read input lines using <>, not read. As in:

    $time = <>;   chomp $time;

    [download]
    You should probably do better matching of the specified $time against the values in the .dat file. E.g. 
    while (<$fh>)
{
   chomp;
   my( $n, $i, $t ) = split;
   $found = 1 if $t eq $time;
}

    [download]
    But where is $studentNumber coming from?

    jdporter
    The 6th Rule of Perl Club is -- There is no Rule #6.

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Re: updating file
by Art_XIV (Hermit) on Apr 08, 2004 at 17:40 UTC

    Homework Hint: By the look of your array of shifts...

    my @shifts = qw( 5:00am 5:30am 6:00am 6:30am 7:00am 7:30am 8:00am 8:30am 9:00am );

    it seems quite easy to advance an hour by advancing the index of @shifts by two. Don't forget the around-the-corner logic if necessary.

    Hanlon's Razor - "Never attribute to malice that which can be adequately explained by stupidity"
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