how to replace a string with a dynamic string

Question

Case 1.

I have a string of alphabets like fthhdtrhththjgyhjdtygbh. Using regex I want to change it to ftxxxxxxxxxxxxxxxxxxxxx, i.e, keep the first two letters and replace the rest by x.

After a lot of googling, I achieved this:

s/^(\w\w)(\w+)/$1 . "x" x length($2)/e;

Case 2.

I have a string of alphabets like sdsABCDEABCDEABCDEABCDEABCDEsdf. Using regex I want to change it to sdsABCDExyxyxyABCDEsdf, i.e, keep the first and last ABCDE and replace the ABCDE in the middle with xy. I achieved this:

s/ABCDE((ABCDE)+)ABCDE/$len = length($1)\/5; ABCDE."xy"x $len . ABCDE/e;

Problem : I am not happy with my solution to the mentioned problem. Is there any better or neat solution to the mentioned problem.

Contraint : Only one regex have to be used.

Sorry for the poor English in the title and the body of the problem, english isn't my first language. Please ask in comments if anything is not clear.

What's the problem you have with your existing solution?

Shriike
– Shriike

2014-09-04 13:23:52 +00:00
Commented Sep 4, 2014 at 13:23 — Shriike
– Shriike, Commented Sep 4, 2014 at 13:23
It's not, um, neat in my opinion. very complex regexes.

GrSrv
– GrSrv

2014-09-04 13:25:08 +00:00
Commented Sep 4, 2014 at 13:25 — GrSrv
– GrSrv, Commented Sep 4, 2014 at 13:25

Miller · Accepted Answer · 2014-09-04 17:13:42Z

1

Task 1: Simplify the password hider regex

Use a Positive Lookbehind Assertion to replace all word characters preceded by two other word characters. This removes the need for the /e Modifier:

my $str = 'fthhdtrhththjgyhjdtygbh';

$str =~ s/(?<=\w{2})\w/x/g;

print $str;

Outputs:

ftxxxxxxxxxxxxxxxxxxxxx

Task 2: Translate inner repeated pattern regex

Use both a Positive Lookbehind and Lookahead Assertion to replace all ABCDE that are bookended by the same string:

my $str = 'sdsABCDEABCDEABCDEABCDEABCDEsdf';

$str =~ s/(?<=(ABCDE))\1(?=\1)/xy/g;

print $str, "\n";

Output:

sdsABCDExyxyxyABCDEsdf

edited Sep 4, 2014 at 17:13

answered Sep 4, 2014 at 16:40

Miller

35.3k4 gold badges42 silver badges61 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

mpapec · Accepted Answer · 2014-09-04 13:56:34Z

1

One regex, less redundancy using \1 to refer to first captured group,

s|(ABCDE)\K (\1+) (?=\1)| "xy" x (length($2)/length($1)) |xe;

edited Sep 4, 2014 at 13:56

answered Sep 4, 2014 at 13:33

mpapec

50.8k8 gold badges72 silver badges133 bronze badges

Collectives™ on Stack Overflow

how to replace a string with a dynamic string

Case 1.

Case 2.

2 Answers 2

Task 1: Simplify the password hider regex

Task 2: Translate inner repeated pattern regex

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

Case 1.

Case 2.

2 Answers 2

Task 1: Simplify the password hider regex

Task 2: Translate inner repeated pattern regex

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related