Regex to match character in order with one or more character repeating consecutively 3 and more times

user_1341406 0
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For example, I am trying to match the following strings

mmmutex
mmuuuTTex
Muuuuuutex
muteeeeeEexxxx
mMutexXxxx

....and many similar strings.

They must have m, u, t, e and x in order with one or more characters repeating consecutively 3 and more times.

I found the following solution

^(?i).*([mutex])\\1{2}[mutex]*$

but it also matches

xxxxxx
mmmmmm
ttttt
eeeee
uuuuuuuuu

and many more similar like above which I don't want. See this demo on regex101.com.

regex
4 Answers

Maybe this will do:

^(?i).*?(mmm+u+t+e+x+|m+uuu+t+e+x+|m+u+ttt+e+x+|m+u+t+eee+x+|m+u+t+e+xxx+).*$

What it does is: it ensure that at least one of the letters is repeating 3 or more times.

  • .*? ensures that the starting m characters will enter into the capturing group
  • mmm+u+t+e+x+ at least 3 m; or
  • m+uuu+t+e+x+ at least 3 u; or
  • m+u+ttt+e+x+ at least 3 t; or
  • m+u+t+eee+x+ at least 3 e; or
  • m+u+t+e+xxx+ at least 3 x
  • everything in a parentheses, from the start ^ till the end $, but only the mutex variations will be in the captured group \1.

If your engine does not do case insensitive matching, then you will need this to catch the different cases:

^.*?([Mm][Mm][Mm]+[Uu]+[Tt]+[Ee]+[Xx]+|[Mm]+[Uu][Uu][Uu]+[Tt]+[Ee]+[Xx]+|[Mm]+[Uu]+[Tt][Tt][Tt]+[Ee]+[Xx]+|[Mm]+[Uu]+[Tt]+[Ee][Ee][Ee]+[Xx]+|[Mm]+[Uu]+[Tt]+[Ee]+[Xx][Xx][Xx]+).*$
user_142985860

This seems to work:

(?i)^.*(?=.*(.)\1\1)m+u+t+e+x+.*$

How this works:

  • (?i): case-insensitive matching
  • ^.*: start of string followed by any char zero or more times
  • (?=: start of lookahead
  • .*: any char zero or more times
  • (.)\1\1: capturing group, capturing any char that is repeated twice
  • ): end of lookahead
  • m+u+t+e+x+: m, u, t, and x, each occurring one or more times
  • .*$: any char zero or more times until end of string
user_80399780
user_13414060
  1. To achieve consecutive matching characters use:
mutex
  1. To catch possible repeating character, use {1,} which means one or more, or {2,3} which means between two an three repetitions:
m{1,}u{1,}t{1,}e{1,}x{1,}

Finally:

^(?i)m{1,}u{1,}t{1,}e{1,}x{1,}
user_136364590
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