RegEx syntax and efficiency

Question

I know a lot of syntax ( c#,c, vb and so on ) hence my head is pretty full.

So I tend to write regex like this
edit2 : change word RegRex
~~[0-9]{1,}[aA-zZ]{1,}~~

[0-9]{1,}[a-zA-Z]{1,}

No +, ?, \d, ...

Is there performance issues with this syntax?

edit : This question is wider than /d vs [0-9] syntax

Don't know about performance but `[aa-zZ]` does not match what you might expect — Tushar, Dec 11 '15 at 05:39
[Use `[0-9]` instead of `\d`](http://stackoverflow.com/questions/890686/should-i-use-d-or-0-9-to-match-digits-in-a-perl-regex), Regex: `[0-9]+[a-zA-Z]` — Tushar, Dec 11 '15 at 05:42
Possible duplicate of [\d is less efficient than \[0-9\]](http://stackoverflow.com/questions/16621738/d-is-less-efficient-than-0-9) — Identity1, Dec 11 '15 at 05:47

score 2 · Accepted Answer · edited Dec 11 '15 at 06:00

2

In terms of performance {1,} and + are equivalent, but the first has more characters to be read... And {1} is not necessary. That won't make much difference though.

More generally, it is not a matter of preference. If you have to match a numeric ID made of numbers from 1 to a big number, without + (or {1,}, or * using \d twice), that will be difficult

\d+

or

[0-9]+

or

[0-9][0-9]*

if you prefer.

Besides, [aA-zZ] matches a, Z (twice actually) and anything between A and z, including [, ], _ ... (see an ascii table)

edited Dec 11 '15 at 06:00

Tushar

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answered Dec 11 '15 at 05:51

Déjà vu

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I dont understand, wich RegEx i cant write ? big number : ([0-9]{1,}) – Dec 11 '15 at 06:18
`{1,}` is equivalent to `+`, so you are using a `+`... and `*` can also be written `{0,}` – Déjà vu Dec 11 '15 at 06:20
1 to big number [1-9][0-9]* – Dec 11 '15 at 06:20

RegEx syntax and efficiency

1 Answers1