Regular Expression Nested Similar Strings

Question

i have a string like this :

"xxxxxxx File_6547845_Whateverishere_S_Md.Txt yyyyyyyyyyyyy File_14787547_Whateverishere_S.Txt zzzzzzzzzzzzz"

and i want to only match the String that start with "file_number_text" and ends with "_s.txt" NOT "_S_md.txt"

i tried "file_\d+?_.*?_s(?!_)\.txt"

but always match String begins with "File_6547845" contains "yyyyyy" and ends with "_s.Txt"

You want to match whole string or text within the string with your regex? — Niitaku, Jan 23 '17 at 13:24
Can you precise this by editing your question? Let's hope @WiktorStribiżew will see that this is not a duplicate of the question he linked. — Niitaku, Jan 23 '17 at 13:39
Can the file path contain spaces? Try [`/file_\d+_\S*_s\.txt/i`](https://regex101.com/r/L3A2QN/4). — Wiktor Stribiżew, Jan 23 '17 at 13:40
Maybe [`file_\d+_(?:(?!\.txt).)*_s\.txt`](https://regex101.com/r/L3A2QN/5)? — Wiktor Stribiżew, Jan 23 '17 at 13:45

score 0 · Accepted Answer · answered Jan 23 '17 at 13:48

If your file paths cannot contain spaces, just use a more specific pattern insteaf of .*?, say, \S*, 0+ non-whitespace chars:

/file_\d+_\S*_s\.txt/i

See this regex demo

If there can be spaces inside the path, it will be very difficult to come up with a safe pattern. Perhaps, matching anything but the .txt substring can help:

/file_\d+_(?:(?!\.txt).)*_s\.txt/i

See this regex demo, where (?:(?!\.txt).)* matches any 0+ chars that do not start the .txt substring. So, this pattern will go up to the last .txt it can find on the line, and then will backtrack looking for _s.txt. If not found, the match will fail, else, the match will be returned.

Regular Expression Nested Similar Strings

1 Answers1