Compare two strings and highlight mismatch characters in Perl - perl

Question

Consider:
string1 = "AAABBBBBCCCCCDDDDD"
string2 = "AEABBBBBCCECCDDDDD"
output. Where the mismatch (in this case E) will be replaced with HTML tags around E that color it.
A**E**ABBBBBCC**E**CCDDDDD
What I tried so far: XOR, diff and substr. First I need to find the indices then replace those indices with the pattern.

Answer 1

my #x = split '', "AAABBBBBCCCCCDDDDD";
my #y = split '', "AEABBBBBCCECCDDDDD";
my $result = join '',
map { $x[$_] eq $y[$_] ? $y[$_] : "**$y[$_]**" }
0 .. $#y;

Answer 2

Use:
use strict;
use warnings;
my $string1 = 'AAABBBBBCCCCCDDDDD';
my $string2 = 'AEABBBBBCCECCDDDDD';
my $result = '';
for(0 .. length($string1)) {
my $char = substr($string2, $_, 1);
if($char ne substr($string1, $_, 1)) {
$result .= "**$char**";
} else {
$result .= $char;
}
}
print $result;
It prints A**E**ABBBBBCC**E**CCDDDDD and was tested somewhat, but it may contain errors.

Answer 3

use warnings;
use strict;
my ($s1, $s2, $o1, $o2) = ("AAABBBBBCCCCCDDDDD", "AEABBBBBCCECCDDDDD");
my #s1 = split(//, $s1);
my #s2 = split(//, $s2);
my $eq_state = 1;
while (#s1 and #s2) {
if (($s1[0] eq $s2[0]) != $eq_state) {
$o1 .= (!$eq_state) ? "</b>" : "<b>";
$o2 .= (!$eq_state) ? "</b>" : "<b>";
}
$eq_state = $s1[0] eq $s2[0];
$o1.=shift #s1;
$o2.=shift #s2;
}
print "$o1\n$o2\n";
Output
A<b>A</b>ABBBBBCC<b>C</b>CCDDDDD
A<b>E</b>ABBBBBCC<b>E</b>CCDDDDD
A simpler one that only prints out the second string:
use warnings;
use strict;
my ($s1, $s2, $was_eq) = ("AAABBBBBCCCCCDDDDD", "AEABBBBBCCECCDDDDD", 1);
my #s1 = split(//, $s1);
my #s2 = split(//, $s2);
for my $idx (0 .. #s2 -1) {
my $is_eq = $s1[$idx] eq $s2[$idx];
print $is_eq ? "</b>" : "<b>" if ( $was_eq != $is_eq);
$was_eq = $is_eq;
print $s2[$idx];
}
Outout
</b>A<b>E</b>ABBBBBCC<b>E</b>CCDDDDD

Answer 4

This might be memory intensive, for large strings:
use strict;
use warnings;
my $a = "aabbcc";
my $b = "aabdcc";
my #a = split //, $a;
my #b = split //, $b;
my $new_b = '';
for(my $i = 0; $i < scalar(#a); $i++) {
$new_b .= $a[$i] eq $b[$i] ? $b[$i] : "**$b[$i]**";
}
Output
$ test.pl
new_b: aab**d**cc

Answer 5

There are several ways to accomplish this. Below is a possible way to solve this.
my $str1="ABCDEA";
my $str2="AECDEB";
my #old1=split("",$str1);
my #old2=split("",$str2);
my #new;
for my $i (0..$#old1) {
if ($old1[$i] eq $old2[$i] ) {
push (#new, $old2[$i]);
}
else
{
my $elem = "**".$old2[$i]."**";
push (#new , $elem);
}
}
print #new;
The output is:
A**E**CDE**B**

Answer 6

Aligning columns and using the bitwise string operator, "^":
my $a = "aabbccP";
my $b = "aabdccEE";
$_ = $a ^ $b;
s/./ord $& ? "^" : " "/ge;
print "$_\n" for $a, $b, $_;
gives:
aabbccP
aabdccEE
^ ^^