[SOLVED] TC Help: Documentation for regular expressions does not explain ? quantifier

[gdpr deleted 6]

In TC's help about regular expressions, quantifiers such as * , + , {n} , {n,m} , etc. are explained in the section "Iterators".

However, an entry for the ? quantifier (the short form of {0,1}) is missing.

(Well, there is an explanation for the greediness modifier - which also uses the same symbol ?, but no explanation about the quantifier ?.)

[ghisler(Author)]

I'm not aware of such an operator ? - are you sure it means the same as {0,1} ?

[gdpr deleted 6]

I'm not aware of such an operator ? - are you sure it means the same as {0,1} ?

Yes. Try it yourself...

For instance, given a text file with

Code: Select all

Hello
Hullo
Heello

a regex search with the pattern "e?llo" would select "ello" from "Hello", when continuing searching it would select "llo" from "Hullo", and then again "ello" from "Heello".


Or, if you prefer file name search, given four files:

Code: Select all

abc.txt
ac.txt
abbc.txt
adc.txt

a regex search with "ab?c" would find abc.txt and ac.txt, but not abbc.txt nor adc.txt.


The ? quantifier with the meaning of {0,1} is a common basic quantifier in most regex flavours. It is also documented on the TRegExpr website: https://regex.sorokin.engineer/en/latest/regular_expressions.html#quantification (although the wording "similar" for the *,+,? explanations chosen there is also a bit unfortunate, because these quantifiers are not just similar but equivalent to the mentioned {0,} , {1,} and {0,1} notations)

[gdpr deleted 6]

? quantifier now explained in help files for TC 10.00b1a (both english and german).

Thanks!