Python 3 How to get string between two points using regex?

Question

How to get the string between two points using regex or any other library in Python 3?

For eg: Blah blah ABC the string to be retrieved XYZ Blah Blah

ABC and XYZ are variables which denote the start and end of the string which I have to retrieve.

Answer 1

Use ABC and XYZ as anchors with look-behind and look-ahead assertions:

(?<=ABC).*?(?=XYZ)

The (?<=...) look-behind assertion only matches at the location in the text that was preceded by ABC. Similarly, (?=XYZ) matches at the location that is followed by XYZ. Together they form two anchors that limit the .* expression, which matches anything.

You can find all such anchored pieces of text with re.findall():

for matchedtext in re.findall(r'(?<=ABC).*?(?=XYZ)', inputtext):

If ABC and XYZ are variable, you want to use re.escape() (to prevent any of their content from being interpreted as regular expression syntax) on them and interpolate:

re.match(r'(?<={}).*?(?={})'.format(abc, xyz), inputtext)