Question

I am quite new in regular expression so I am having confusion in replacing numbers inside an string.

a="12ab34cde56" 

I want to replace it by 12abXXcde56

b="abc1235ef"

I want to replace it by abcXXXXef

c="1ab12cd"

I want to replace it by 1abXXcd

I am trying those in python and in php, but with no luck. This is what I had in my mind:

^([0-9]+)([a-z]+)(.*)([a-z]+)([0-9]+)$

Answer 1

You can use this regex to capture all digits that is not leading or trailing:

(?<!^|\d)\d+(?!$|\d)

Then in Python, you can supply a function that replace the match with corresponding number of X.

For PHP, you can enable PREG_OFFSET_CAPTURE to know the position of the match, and loop through the list of matches and process them.

Note that with the regex above " 5 ddds" will be changed into " X ddds"