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Regular expression question

 
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# 1  
Old 08-31-2015
Regular expression question
Hi guys,

I need a help with a query. Basically i want to know the difference between (0+01)* and ((0+01)*)* . It seems whatever string can be generated by the first RE can also be generated by second and they should essentially be same. Am i missing something?
# 2  
Old 08-31-2015
There isn't nearly enough information to accurately asses the similarity of the strings that could be matched by these strings:
  1. Are these filename matching patterns, basic regular expressions, extended regular expressions, perl regular expressions, or something else?
  2. If they are BREs, EREs, or perl REs; what utility or function is evaluating these REs?
  3. If these REs are used in something like a substitution operation (e.g., ex s/RE/rep/flags, awk sub(RE, rep, string) or gsub(RE, rep, string)) is there a back reference in the replacement string (rep)?
If these REs are filename matching patterns, they don't even come close to matching the same strings.

If there are back references to parts of the REs, the number of open parentheses affect the number used in the back references.
 
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