Here's a short Perl program for you to mull over.
$
$
$ # show the contents of file1, file2 and file3
$
$ cat -n file1
1 ARTPHDFGAA
2 DKDXCSIKER
3 QQELKRNIKJ
4 OJUUXGFBVP
$
$ cat -n file2
1 ARTGHHYESA
2 AGCBCHBCRB
3 CWWENBYITN
4 WMVXVPNANW
$
$ cat -n file3
1 ARTPOLYWEA
2 PXCSMTWUND
3 MNBLYALUUO
4 XPRAYHLPHT
$
$ # show the content of the Perl program
$
$ cat -n string_operations.pl
1 #perl -w
2 sub print_legend {
3 print "
4 LEGEND =>
5 (1) Characters common in file1, file2, file3.
6 (2) Characters common in file1 and file2.
7 (3) Characters common in file2 and file3.
8 (4) Characters common in file3 and file1.
9 (5) Characters in file1 that are absent from file2 and file3.
10 (6) Characters in file2 that are absent from file3 and file1.
11 (7) Characters in file3 that are absent from file1 and file2.
12 ";
13 }
14 sub common_all {
15 $n = shift;
16 $x1 = shift;
17 $x2 = shift;
18 $x3 = shift; # load all arguments to work on
19 print "\n","="x20," Line no. $n\n"; # print something nice
20 print "(1) ";
21 for ($j=0; $j<=length($x1); $j++) { # walk through the 1st string
22 if ( substr($x1,$j,1) eq substr($x2,$j,1) && # if 1st and 2nd string have identical character
23 substr($x2,$j,1) eq substr($x3,$j,1)) { # that is identical to that of 3rd string, then
24 print substr($x1,$j,1); # print it
25 } else {
26 print " "; # otherwise, print a blank space
27 }
28 }
29 print "\n";
30 }
31 sub common_xy {
32 $n = shift;
33 $x1 = shift;
34 $x2 = shift;
35 print "($n) ";
36 for ($j=0; $j<=length($x1); $j++) { # walk through the 1st string
37 if (substr($x1,$j,1) eq substr($x2,$j,1)) { # if 1st and 2nd string have identical character
38 print substr($x1,$j,1); # then print it
39 } else {
40 print " "; # otherwise, print a blank space
41 }
42 }
43 print "\n";
44 }
45 sub in_x_not_in_yz {
46 $n = shift;
47 $x1 = shift;
48 $x2 = shift;
49 $x3 = shift;
50 print "($n) ";
51 for ($j=0; $j<=length($x1); $j++) { # walk through the 1st string
52 if (substr($x1,$j,1) ne substr($x2,$j,1) && # if current character is not in 2nd string
53 substr($x1,$j,1) ne substr($x3,$j,1)) { # and not in 3rd string either, then
54 print substr($x1,$j,1); # print it
55 } else {
56 print " "; # otherwise, print a blank space
57 }
58 }
59 print "\n";
60 }
61
62 ## Main program starts here
63 print_legend;
64
65 # Open the 3 files and load data into 3 arrays
66 open (F1, "<", "file1") or die "Can't open file1: $!";
67 chomp(@a1 = <F1>);
68 close (F1) or die "Can't close file1: $!";
69 open (F2, "<", "file2") or die "Can't open file2: $!";
70 chomp(@a2 = <F2>);
71 close (F2) or die "Can't close file2: $!";
72 open (F3, "<", "file3") or die "Can't open file3: $!";
73 chomp(@a3 = <F3>);
74 close (F3) or die "Can't close file3: $!";
75
76 # Start processing the arrays now
77 for ($i=0; $i<=$#a1; $i++) {
78 common_all ($i+1, $a1[$i], $a2[$i], $a3[$i]); # Common in all three
79 common_xy (2, $a1[$i], $a2[$i]); # Common in file1 and file2
80 common_xy (3, $a2[$i], $a3[$i]); # Common in file2 and file3
81 common_xy (4, $a3[$i], $a1[$i]); # Common in file3 and file1
82 in_x_not_in_yz (5, $a1[$i], $a2[$i], $a3[$i]); # In file1 but not in file2 and file3
83 in_x_not_in_yz (6, $a2[$i], $a3[$i], $a1[$i]); # In file2 but not in file3 and file1
84 in_x_not_in_yz (7, $a3[$i], $a1[$i], $a2[$i]); # In file3 but not in file1 and file2
85 }
86 print "\n";
$
$
$ # Now run the Perl program
$
$ perl string_operations.pl
LEGEND =>
(1) Characters common in file1, file2, file3.
(2) Characters common in file1 and file2.
(3) Characters common in file2 and file3.
(4) Characters common in file3 and file1.
(5) Characters in file1 that are absent from file2 and file3.
(6) Characters in file2 that are absent from file3 and file1.
(7) Characters in file3 that are absent from file1 and file2.
==================== Line no. 1
(1) ART A
(2) ART H A
(3) ART Y A
(4) ARTP A
(5) DFGA
(6) G H ES
(7) OL WE
==================== Line no. 2
(1)
(2) C
(3) C
(4)
(5) DKDX SIKER
(6) AG B HBCRB
(7) PX SMTWUND
==================== Line no. 3
(1)
(2) I
(3)
(4) L
(5) QQE KRN KJ
(6) CWWENBY TN
(7) MNB YALUUO
==================== Line no. 4
(1)
(2)
(3)
(4)
(5) OJUUXGFBVP
(6) WMVXVPNANW
(7) XPRAYHLPHT
$
$
Hopefully, the inline script comments are self-explanatory.
tyler_durden
