substr( $string, rindex( $string, $find ), 1, $replace );
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$find = 's';
$replace = 'X';
$string = 'Snakes';
$string =~ s/$find$/$replace/;
print $string, "\n";
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Personally I'd go down the regex route too for preference. If the find/replace chars that you're using are always the same then you can improve the effeciency with just:

$string = 'Snakes';
$string =~ s/s$/X/;
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If you want to take the substr() route then try:

substr($string,-1,1,'X');
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That will replace the last character whatever it is with the X. For more details I'd also point you towards the perldocs - if you don't have access to the perldoc function then look it up on http://www.perldoc.com.

--- Jay

All code is untested unless otherwise stated.

If you always want the last letter, you could match:

$string =~ s/.$/X/;
## or
$letter = 'X';
$string =~ s/.$/$letter/;
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As opposed to the substr use.
radiantmatrix
require General::Disclaimer;

What about replacing the last occurance of 's' in the word 'systematic'? I think the OP should have stated the question more clearly, that he wants the last occurance of a certain letter, not the last letter of the string.

substr($variable, rindex($variable,$tofind), length($tofind), $replace
+ment) if rindex($variable,$tofind) > -1;
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It seems to me that this was recently posted about on this site.

#!/usr/bin/perl
use strict;

my $find = "r";
my $replace = "X";

my $input = "superfrink";

my $tmp = reverse $input;
$tmp =~ s/$find/$replace/;
my $output = reverse $tmp;

print "input: $input \n";
print "output: $output \n";
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Update: Here is the sample output.


frink@scanbox:~ $ ./397370.pl 
input: superfrink 
output: superfXink 
frink@scanbox:~ $
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#!/usr/bin/perl

use strict;
use warnings;

my $tofind="s";
my $replacement="X";
my $variable="snaskes";

print "Before: $variable\n";

$variable =~ s/$tofind[^$tofind]*$/$replacement/;

# OR
# $variable =~ s/$tofind(?![$tofind])$/$replacement/;

print "After: $variable\n";
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The main version does the right thing, but the alternative doesn't - negative lookahead will look for something immediately following, so:

  $variable =~ s/$tofind(?![$tofind])$/$replacement/;
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means "find the letter, not followed by the letter again, but followed by the end anchor". I think you want instead:

  $variable =~ s/$tofind(?!.*$tofind)/$replacement/;
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ie "find the letter, not followed by (zero or more characters and) the letter again".

Also, the [$tofind] character class is the same as $tofind itself when it refers to a single letter, but doesn't do the right thing if $tofind is something more complex.

Hugo

my $tofind="s";
my $replacement="X";
my $variable="snaskes";

my $tmp = chop $variable;
$variable .= $tmp eq $tofind ? $replacement : $tmp;

print $variable;
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s/(.*)$tofind(.*)/$1$replacement$2/

It relies upon the greediness of the regex engine to match as much as possible as soon as possible.

my $tofind="s";
my $replacement="X";
my $variable="snaskes";

substr($variable, -1, 1) = $replacement if (substr($variable, -1, 1) e
+q $tofind);

print "$variable\n";
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Update: Thanks to the CB folks for pointing out the mistake! Edited.

I noted this got downvoted, which is fine... I'm not seeking argument to that

I would appreciate knowing, however, why. I'm always wanting to improve my skills, and if I've done something unknowingly wrong here, please let me know so I can correct it in the future

I think I've shown in the past that I'm willing to learn from my own mistakes when shown why

Maybe others here take offense to being corrected, but I appreciate it.

Trek

$variable = reverse $string;
$variable =~ s/$tofind/$replace/;
$variable = reverse $string;
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