دروس الوحدة (3/4)
مجموعات غير ملتقطة: `(؟:...)`
Often parentheses are needed only to group (quantify, alternate)
and NOT to extract the value. In that case use the non-capturing
version: (?:...). It works identically to (...) but does not create
a numbered group.
Pattern: (?:https?)://(\w+\.\w+)
Sample: https://example.com e http://test.org
Match e gruppi:
match = "https://example.com" gruppo1 = "example.com"
match = "http://test.org" gruppo1 = "test.org"(?:https?) groups the scheme to apply the ? quantifier, but we are
not interested in extracting https as a group: group 1 is directly the
domain.
Why use it
- Readability: the reader immediately understands that the group is only there for structure, not to extract a value.
- Performance: the engine does not have to store the group's match.
- Clean numbering: numbered groups stay aligned with "information I actually need", without interference.
Optimizing with non-capturing groups
Using (?:...) tells the engine to apply grouping and quantifier rules without wasting memory storing intermediate match results. This is highly recommended in heavy loops or very long text processing.
Try it
Extract the domain (`example.com`, `test.org`…) from every URL in the text. Use `(?:https?)` for the protocol (no need to capture it) and a single group for the domain.
إظهار التلميح
Change the first group from (https?) to (?:https?): no need to capture it, you only want the domain.
الحل متاح بعد 3 من المحاولات
Review exercise
Find every repetition of `ab` as a single match, but WITHOUT capturing the group (since you only need the whole match).
إظهار التلميح
Same syntax as the previous lesson, but with (?:ab)+ instead of (ab)+.
الحل متاح بعد 3 من المحاولات
Additional challenge
Find price digits followed optionally by decimal parts inside a non-capturing group, e.g. `100` or `100.50`.
إظهار التلميح
Use (?:\.\d{2})? to make the decimal part optional without capturing it.
الحل متاح بعد 3 من المحاولات