Negative lookbehind regular expression not working on Notepad++

guy038

Hello, @dr-ramaanand and All,

Ah, I just having some spare time to answer your specific problem !

As I said in a previous post, you cannot use look-behinds as they do NOT support variable quantifiers ! That’s why I proposed a method with the ((SKIP)(*F) feature, which works properly.

In order to found out other methods, let’s begin with a simplified problem :

Starting with this INPUT text :

DEF  ABCDEF   ABC     DEF  ABCDEF   XYZDEF   ABCDEF

The following regex S/R :

FIND (?-is)ABCDEF(*SKIP)(*F)|DEF

REPLACE 12345

Matches only the DEF string when NOT preceded with the ABC string

After the replacement, we get this OUTPUT :

12345  ABCDEF   ABC     12345  ABCDEF   XYZ12345   ABCDEF

If DEF is preceded by ABC, NO replacement occurs
If DEF is NOT preceded by ABC it replaces the string DEF by the string 12345

Now, using the same INPUT text :

The following regex S/R :

FIND (?-is)ABCDEF\K|(DEF)

REPLACE ?{1}12345

Detect an empty match, when the DEF string is preceded by the ABC string
Detect some selected text, when the DEF string is NOT preceded by the ABC string

But, due to the group, in the final part of the regex and due to the conditional replacement, it would produce this OUTPUT :

12345  ABCDEF   ABC     12345  ABCDEF   XYZ12345   ABCDEF

As previously :

if DEF is preceded by ABC, NO replacement occurs
if DEF is NOT preceded by ABC it replaces the string DEF by the string 12345

Let’s apply this new regex S/R to your problem. Thus, from this regex :

FIND (?:<span\b[^>]*?color\s*:\s*black[^>]*>\s*|<p\b[^>]*?color\s*:\s*black[^>]*>\s*<span\b[^>]*>\s*)<code\s*style="background-color:\s*transparent;">(*SKIP)(*F)|<code\s*style="background-color:\s*transparent;">

If we simply replace the (*SKIP)(*F) part by \K AND if we put all the right branch of the alternative within a group, this S/R becomes as :

FIND (?:<span\b[^>]*?color\s*:\s*black[^>]*>\s*|<p\b[^>]*?color\s*:\s*black[^>]*>\s*<span\b[^>]*>\s*)<code\s*style="background-color:\s*transparent;">\K|(<code\s*style="background-color:\s*transparent;">)

REPLACE ?1[REPLACED text]

When just searching, the non-interesting matches will be notified as an empty match and the correct matches will be notified as selected text.

And if a global replacement occur, with the Replace All button, this regex would just replace the same occurrences as with the (*SKIP)(*F) method !

Try against your INPUT text, pasted in a new tab : you should get 2 empty matchs and 4 selected range of characters. And, after replacement you’ll left with four zones [REPLACED text].

<html>
<p style="font-family: &quot;verdana&quot;; font-size: 18px; color: black; line-height: 18px; text-align: justify; font-style: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; background-color: cyan;"><span style="font-size: 13.5pt; font-family: &quot;Verdana&quot;,&quot;sans-serif&quot;;"><code style="background-color: transparent;">•••••<b>some text here</b></code></span></p>
<span><span style="font-size: 13.5pt; font-family: &quot;Verdana&quot;,&quot;sans-serif&quot;; background-color: cyan;"><code style="background-color: transparent;"><b>some text here</b></code></span>


<code style="background-color: transparent;">


<p style="font-family: &quot;verdana&quot;; font-size: 18px; color: cyan; line-height: 18px; text-align: justify; font-style: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; background-color: cyan;"><span style="color: black; font-size: 13.5pt; font-family: &quot;Verdana&quot;,&quot;sans-serif&quot;;"><code style="background-color: transparent;">•••••<b>some text here</b></code></span></p>


<span><span style="font-size: 13.5pt; font-family: &quot;Verdana&quot;,&quot;sans-serif&quot;; background-color: cyan;"><code style="background-color: transparent;"><b>some text here</b></code></span>


<p style="font-family: &quot;verdana&quot;; font-size: 18px; color: cyan; line-height: 18px; text-align: justify; font-style: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; background-color: navy;"><span style="font-size: 13.5pt; font-family: &quot;Verdana&quot;,&quot;sans-serif&quot;;"><code style="background-color: transparent;"><b>some text here</b></code></span></p>
</html>

Now, it’s not the end of the story ! Imagine that, against the same INPUT text, below :

DEF  ABCDEF   ABC     DEF  ABCDEF   XYZDEF   ABCDEF

We use this simplified regex S/R :

FIND (?-is)ABC\KDEF|(DEF)

REPLACE ?{1}12345

Note that, this time, the \K is placed before the string DEF

So, it would match any string DEF, whatever it’s preceded or NOT by the ABC string

But, due to the group, in the final part of the regex and due to the conditional replacement, We would get this new OUTPUT text, after a click on the Replace All button

12345  ABC   ABC     12345  ABC   XYZ12345   ABC

if DEF is preceded by ABC, it replaces the string ABCDEF by the string ABC
if DEF is NOT preceded by ABC it replaces the string DEF by the string 12345

This S/R is a variant of the previous one which may interest you in some cases !

In short, I cannot imagine, presently, other methods than the two above, with (SKIP)(*F) or \K

Remember, that the look-arounds structure does not seem appropriate to your style of search !

Best Regards,

guy038

dr ramaanand

@guy038 Oui, merci beaucoup!

dr ramaanand

This post is deleted!