ITNW 2310 - PERL
Allan Kochis,Adjunct Professor - CIT

Arrays

  1. Split and Join
    Split splits up a string by some delimiter (whitespace by default) and returns and array.
    Join is the inverse of split, it joins the elements of an array into a single string with a delimiter.
    PerlOutput 
    #!/usr/bin/perl -w

$string=`date`;
chomp($string);

print "String ".$string."\n\n";

@array=split(/ /,$string);

print @array." elements \n\n";
for($i=0; $i < @array ; $i++) {
   print "element $i = $array[$i] \n";
}
print "\n";
$string=join(":",@array);
print "String ".$string."\n\n";

@array=split(/:/,$string);

print @array." elements \n\n";
for($i=0; $i < @array ; $i++) {
   print "element $i = $array[$i] \n";
}


    String Wed Sep 14 08:20:05 CST 2005

6 elements

element 0 = Wed
element 1 = Sep
element 2 = 14
element 3 = 08:20:05
element 4 = CST
element 5 = 2005

String Wed:Sep:14:08:20:05:CST:2005

8 elements

element 0 = Wed
element 1 = Sep
element 2 = 14
element 3 = 08
element 4 = 20
element 5 = 05
element 6 = CST
element 7 = 2005

  2. Splice
    splice(array, offset, length, list);
    PerlOutput 
    #!/usr/bin/perl -w

$string=`date`;
chomp($string);

print "String ".$string."\n\n";

@array=split(/ /,$string);

print @array." elements \n\n";
for($i=0; $i < @array ; $i++) {
   print "element $i = $array[$i] \n";
}
print "\n";

splice(@array,2,2,01,02,03,04);


print @array." elements \n\n";
for($i=0; $i < @array ; $i++) {
   print "element $i = $array[$i] \n";
}
print "\n";

splice(@array,2,2);

print @array." elements \n\n";
for($i=0; $i < @array ; $i++) {
   print "element $i = $array[$i] \n";
}
print "\n";

splice(@array,2);

print @array." elements \n\n";
for($i=0; $i < @array ; $i++) {
   print "element $i = $array[$i] \n";
}
print "\n";


    String Wed Sep 14 08:31:48 CST 2005

6 elements

element 0 = Wed
element 1 = Sep
element 2 = 14
element 3 = 08:31:48
element 4 = CST
element 5 = 2005

8 elements

element 0 = Wed
element 1 = Sep
element 2 = 1
element 3 = 2
element 4 = 3
element 5 = 4
element 6 = CST
element 7 = 2005

6 elements

element 0 = Wed
element 1 = Sep
element 2 = 3
element 3 = 4
element 4 = CST
element 5 = 2005

2 elements

element 0 = Wed
element 1 = Sep

  3. Sort
    PerlOutput 
    #!/usr/bin/perl -w


for($i=0; $i <10; $i++) {
   $array[$i]=rand()*10;
}

print @array." elements \n\n";
for($i=0; $i < @array ; $i++) {
   print "element $i = $array[$i] \n";
}
print "\n";

@array=sort(@array);

print @array." elements \n\n";
for($i=0; $i < @array ; $i++) {
   print "element $i = $array[$i] \n";
}
print "\n";


    10 elements

element 0 = 3.06604555183188
element 1 = 4.58620085005776
element 2 = 8.27025464308587
element 3 = 4.53334868742736
element 4 = 5.73902871122375
element 5 = 0.411092748254163
element 6 = 8.20418054374695
element 7 = 8.30017465673414
element 8 = 3.8698673689797
element 9 = 0.356841239270125

10 elements

element 0 = 0.356841239270125
element 1 = 0.411092748254163
element 2 = 3.06604555183188
element 3 = 3.8698673689797
element 4 = 4.53334868742736
element 5 = 4.58620085005776
element 6 = 5.73902871122375
element 7 = 8.20418054374695
element 8 = 8.27025464308587
element 9 = 8.30017465673414

  4. map
    PerlOutput 
    #!/usr/bin/perl -w


for($i=0; $i <10; $i++) {
   $array[$i]=$i;
}

print @array." elements \n\n";
for($i=0; $i < @array ; $i++) {
   print "element $i = $array[$i] \n";
}
print "\n";

@array=map {$_+=4 } @array;

print @array." elements \n\n";
for($i=0; $i < @array ; $i++) {
   print "element $i = $array[$i] \n";
}
print "\n";


    10 elements

element 0 = 0
element 1 = 1
element 2 = 2
element 3 = 3
element 4 = 4
element 5 = 5
element 6 = 6
element 7 = 7
element 8 = 8
element 9 = 9

10 elements

element 0 = 4
element 1 = 5
element 2 = 6
element 3 = 7
element 4 = 8
element 5 = 9
element 6 = 10
element 7 = 11
element 8 = 12
element 9 = 13

  5. Assignment 2 the perly way
    PerlOutput 
    #!/usr/bin/perl

$string="0123456789";
@a=split(//,$string);
@ord=map ord,@a;
@left=map {$_>>4} @ord;
@right=map {$_&0x0F} @ord;

print join(//,@a)."\n";
print join(//,@left)."\n";
print join(//,@right)."\n";


    0111213141516171819
3131313131313131313
0111213141516171819

  6. A 2 dimension like array (Very Cish)
    PerlOutput 
    #!/usr/bin/perl -w
#
#
sub map  {
#
#  given a row and column create a single subscript
#
  my $x = $_[0];
  my $y = $_[1];
  my $z;

  $z=$x*$columns +$y;
  return $z;
}

$rows=8;
$columns=8;
$#array=$rows * $columns;

for $row ( 0 .. $rows-1) {
   for $col ( 0 .. $columns-1) {
        $array[&map($row,$col)]= ($row+1) * ($col+1);
   }
}

for $row ( 0 .. $rows-1)  {
     for $col ( 0 .. $columns-1 ) {
         printf("%3d ", $array[&map($row,$col)]);
     }
     print "\n";
}


      1   2   3   4   5   6   7   8 
  2   4   6   8  10  12  14  16 
  3   6   9  12  15  18  21  24 
  4   8  12  16  20  24  28  32 
  5  10  15  20  25  30  35  40 
  6  12  18  24  30  36  42  48 
  7  14  21  28  35  42  49  56 
  8  16  24  32  40  48  56  64

  7. Pascal's Triangle
    PerlOutput 
    #!/usr/bin/perl -w
#
#
sub map  {
#
#  given a row and column create a single subscript
#
  my $x = $_[0];
  my $y = $_[1];
  my $z;

  $z=($x*($x+1))/2+$y;
  return $z;
}

$rows=10;
$#tri=($rows*($rows +1))/2;

for $row ( 0 .. $rows-1) {
   for $col ( 0 .. $row) {
        if($col == 0 || $col == $row) {
            $tri[&map($row,$col)]=1;
        } else {
            $tri[&map($row,$col)]=$tri[&map($row-1,$col-1)] +
                                  $tri[&map($row-1,$col)]; 
        }  
   }
}

for $row ( 0 .. $rows-1)  {
     $line="";
     for $col ( 0 .. $row ) {
        $line.=sprintf("%d ", $tri[&map($row,$col)]);
     }
     $blanks=(80 -(length $line))/2;
     print " " x $blanks,$line,"\n";
}


                                           1 
                                      1 1 
                                     1 2 1 
                                    1 3 3 1 
                                   1 4 6 4 1 
                                 1 5 10 10 5 1 
                               1 6 15 20 15 6 1 
                              1 7 21 35 35 21 7 1 
                            1 8 28 56 70 56 28 8 1 
                          1 9 36 84 126 126 84 36 9 1
© Allan Kochis Last revision 9/14/2005