my $s = "I have red stuff, blue stuff, orange stuff, and more red stuf
+f.";
my @search = ("red", "orange", "blue");
my @replace = ("yellow", "black", "green");
my %replacements;
@replacements{ @search } = @replace;    # use a hash slice to populate
+ the search=>replace pairs.
my $re = join '|', @search;
$s =~ s/\b($re)\b/$replacements{$1}/g;
print $s;
[download]

This question came up a few months ago in Substitute 'bad words' with 'good words' according to lists. You might want a take a look there.

hmm,

@search = ("red", "orange", "blue");
@replace = ("yellow", "black", "green"); 
$text = "my pig is red, my orange is orange and the sky is blue"; 
foreach (0..$#search) { 
    $text =~ s/$search[$_]/$replace[$_]/;
} 
print $text,"\n"
__END__
my pig is yellow, my black is orange and the sky is green
[download]

not a beauty, but works...

#!/bin/perl5

use strict;
use warnings;

my @search = ("red", "orange", "blue");
my @replace = ("yellow", "black", "green");
my %replacements;
@replacements{ @search } = @replace; 

my $string = q(red orange blue blue);

for my $key (keys %replacements){
  $string =~ s/$key/$replacements{$key}/ge;
}
[download]

The major difference is that your loop makes multiple passes through the string, and davidrw's does not. Depending on the size of the string and how many search terms there are, the performance difference can be quite significant.

---

Caution: Contents may have been coded under pressure.

s/\b(\w+)\b/ $subst{$1} || $1/ge;
[download]