替换两个字符串之间所有出现的字符

Question

I want to replace all space occurrences between string1 and string2 with a _ character on all lines of a text document using Notepad++.

Examples:

string1 this is a first example string2
string1 this is a second example string2

Expected result:

string1_this_is_a_first_example_string2
string1_this_is_a_second_example_string2

I tried this expression (?<=string1)(\s*)(?=string2) , but it didn't work.

Answer 1

You may use

Find What : (?:\G(??^)|string1)(:?(.?string1|string2)?)*.\K\h(?=.*string2)
Replace With : _

See the regex demo .

NOTE :

• If you need to only match regular spaces, replace \h with a regular space
• A more appropriate check for the end of the previous successful match is \G(??^(?<![\s\S])) , but if your expected matches are on a single line, you might go on using \G(?!^) .

Details

• (?:\G(?!^)|string1) - either the end of the previous match (but not start of a line) or string1
• (?:(?.string1|string2)?)*? - any char, 0 or more times, but as few as possible, that is not starting string1 or string2 char sequence
• \K - discard the text matched so far
• \h - any horizontal whitespace
• (?=.*string2) - there must be a string2 after any 0 or more chars other than line break chars as many as possible immediately to the right of the current location.