Regex Use start of line end of line signs or in different context

Question

While doing some small regex task I came upon this problem  I have a string that is a list of tags that looks e g like this      foo bar qux garp wobble thud  What I needed to do was to check if a certain tag  e g   garp  was in this list   What it finally matches is not really important  just if there is a match or not    My first and a bit stupid try at this was to use the following regex          garp      My idea was that before  garp  there should either be the start of the line string or a comma  after  garp  there should be either a comma or the end of the line string   Now  it is instantly obvious that this regex is wrong  Both   and   change their behaviour in the context of the character class       What I finally came up with is the following       garp   garp   garp   garp   This regex just handles the 4 cases one by one   Tag at beginning of list  in the center  at the end  or as the only element of the list   The last regex is somehow a bit ugly in my eyes and just for funs sake I d like to make it a bit more elegant   Is there a way how the start of line end of line characters    and    can be used in the context of character classes   EDIT  Ok  some more info was wished so here it is  I m using this within an Oracle SQL statement  This sadly does not allow any look-around assertions but as I m only interested if there is a match or not  and not what is matched  this does not really affect me here  The tags can contain non-alphabetical characters like - or   so  bgarp b would not work  Also one tag can contain an other tag as SilentGhost said  so  garp  doesnt work either

User · Accepted Answer

You can t use   and   in character classes in the way you wish - they will be interpreted literally  but you can use an alternation to achieve the same effect        garp

User · Answer

you just need to use word boundary   b  instead of   and      bgarp b

User · Answer

Just use look-arounds to solve this      lt      garp          The difference with look-arounds and just regular groups are that with regular groups the comma would be part of the match  and with look-arounds it wouldn t  In this case it doesn t make a difference though

[regex] Regex: Use start of line/end of line signs (^ or $) in different context

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