yesterday's time

I just read FAQ on finding out yesterday's time.

I see that one of the easy way to find out is

my $date = scalar localtime( ( time() - ( 24 * 60 * 60 ) ) );
print "$date\n";

and it works fine for me

I also see lot of modules that will make life easier for beginners.. but 
since I was learning reference, I wanted to try this on my own
since Leap year is not a huge factor, so

my @[EMAIL PROTECTED]
 = (1..31);
my @[EMAIL PROTECTED]
 = (1..29);
my @[EMAIL PROTECTED]
 = (1..31);
my @[EMAIL PROTECTED]
 = (1..30);
my @[EMAIL PROTECTED]
 = (1..31);
my @[EMAIL PROTECTED]
 = (1..30);
my @[EMAIL PROTECTED]
 = (1..31);
my @[EMAIL PROTECTED]
 = (1..31);
my @[EMAIL PROTECTED]
 = (1..30);
my @[EMAIL PROTECTED]
 = (1..31);
my @[EMAIL PROTECTED]
 = (1..30);
my @[EMAIL PROTECTED]
 = (1..31);

my @[EMAIL PROTECTED]
 = [ @[EMAIL PROTECTED]
 my $i ( 0 .. $#cal_r ) {
    for my $j ( 0 .. $#{ $cal_r[ $i ] } ) {
           print "$cal_r[ $i ][ $j ]\n";
    }
}

and then just check to see if it's first day of the month and if it is, 
go through @[EMAIL PROTECTED]
 and find the previous month and find the last array
item..
Algorithm seems to be correct but I cannot get to the item the way I 
thought I could.

What would be the correct syntax if I knew the date? say Apr 1st to find 
the yesterday's date given above?

I was thinking something along the line of

for my $i ( 0 .. $#cal_r ) {
    if ($cal_r[$i][0]) {
          print "yesterday is $cal_r[$i-1][lastday]\n"
    }
}