Regular expression to change user input

I am doing a search on my database. If the user enters eg. "foo bar" I want to display rows that have both "foo" AND "bar".

My SQL syntax looks like this: SELECT * FROM t1 WHERE MATCH (t1.foo_desc, t2.bar_desc) AGAINST ('+foo* +bar*')

How can I change the user input "foo bar" into "+foo* +bar*" using a regular expression in PHP?

From stackoverflow

• $match = '+' . implode('* +', explode(' ', $input)) . '*';
  

  This assumes that the input isn't an empty string;

  Edit: As @Bart S points out, str_replace (or mb_str_replace if you're dealing with multibyte characters) would be even simpler...

  $match = '+' . str_replace(' ', '* +', $input) . '*';
  

  Bart S. : Why not use str_replace?

  soulmerge : +1 I don't understand why people always demand regular expressions for trivial tasks

  J. Steen : A programmer has a problem. He decides to solve this using regular expressions. Now he has two problems.

  Tomalak : +1 Thinking about it, I don't know either. ;-) However, *some* normalization/checking should be done in any case.

  Tomalak : @metaphor: Now that's a smart quote. I've never heard it before.

  Wil : Works, but explode parameters should be the other way around: explode($input, ' ') -> explode(' ', $input)

  Greg : Oops - fixed...

  Gumbo : What if there are two ore more spaces between two words? Your solution would replace those additional spaces too and turn `foo bar` (two space between) into "+foo* +* +bar*". So why not just a reg… ;)

• You should use \b and \B to identify the word/not-word boundaries, and thus insert your +/*.

• First, trim the user input and remove anything strange (punctuation, quotes, basically everything "\W", except white space of course).

  Then, substitute:

  (?<=\w)\b
  

  with

  "*"
  

  and:

  \b(?=\w)
  

  with

  "+"
  

• For those interested in the MATCH...AGAINST syntax This article is a decent starting point if you haven't used it before.

• I would use a regular expression to replace the spaces between two words by * +:

  '+' . preg_replace('/\s+/', '* +', trim($input)) . '*'
  

  Edit   Basically this is an implementation to what Tomalak said just with \s instead of \W.