StringRegExpReplace Replace a letter if the previous char was a digit

[Qwerty212]

Hello from Barcelona.

I have a doubt about StringRegExpReplace

I'm populating some listviews with the results of a SQL Query and one of the strings can look like this:

"Bimate, 8-15M + . Mesh."

I want to change the M that I have marked in Bold font with this symbol: µ

The rule to know wich M I want to change is that it will always has a digit in the previous char.

I have tried

_GUICtrlListView_AddSubItem($listview, $n, StringReplace($query[$n][$s], "M", "µ", 0, 1), $s)

But, it also changes the second M (The one from "Mesh.")

I have tried searching for the capital M position in the string, but it can happen that the original string ends with a M ("Bimate, 8-15M")

The only reliable pattern for the current querys and for unknow future ones is that the "M" that I need to change is always preceded by a digit.

Any help would be trully appreciated.

Edited December 30, 2019 by Qwerty212

[jchd]

Try this:

_GUICtrlListView_AddSubItem($listview, $n, StringReplace($query[$n][$s], "(?<=\d)M", "µ", 0, 1), $s)

The sequence (?<=\d) is a look-behind assertion. In plain English, it means: "what follows [here the letter M] must be immediately preceded by one digit".

See the help about StringRegExp function.

Edited December 31, 2019 by jchd
Typo fixed in text.

[pixelsearch]

@jchd

$res = StringRegExpReplace("Bimate, 8-15M + .Mesh", "(?<=\d)M", "µ")
$res = StringRegExpReplace("Bimate, 8-15M + .Mesh", "(\d)M", "$1µ")

To improve my little knowledge about RegExp, could you please confirm that both solutions are strictly equivalent ?
Thanks

Edited December 30, 2019 by pixelsearch

[mikell]

9 hours ago, jchd said:

The sequence (?<=\D) ... means: "what follows ... must be immediately preceded by one digit"

Warning , typo inside 
 

@pixelsearch
Both solutions work but I personally prefer the first one because it matches the requirement strictly

[jguinch]

personally , I prefer to use \K instead of the lookbehind method when possible, because a lookbehind expression cannot be used with non-fixed length of characters

 

[jchd]

Typo fixed, sorry for that mistake.

[Qwerty212]

Thanks a lot to you all for the help!!