OK, how do i make subexpression?

Wikipedia says:
(ab)* matches "", "ab", "abab", "ababab", and so on.

i implemented this and tested on my PC, it worked, but when i submit solutions with it, it gives wrong answer

lets say i want to write BLAH 5 times, is this correct:
(BLAH){5}

  • created

    May '08
  • last reply

    May '08
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Wikipedia is not a very good source here, as POSIX extended regular expressions are used. It says 'backslash is reversed for some character'. Specifically, it means that instead of '(' and ')' you have to write '(' and ')'; but to match literal parenthesis '(' and ')' has to be used.

The same goes for '{' and '}', but you already got that right.
The correct RE would thus be (BLAH){5}