Remove all special characters from a string

Question

I am facing an issue with URLs  I want to be able to convert titles that could contain anything and have them stripped of all special characters so they only have letters and numbers and of course I would like to replace spaces with hyphens   How would this be done  I ve heard a lot about regular expressions  regex  being used

User · Answer

Here  check out this function   function seo friendly url  string        string   str replace array                   string        string   preg replace          U        string        string   preg replace    amp  amp      a-z0-9    i    -    string        string   htmlentities  string  ENT COMPAT   utf-8         string   preg replace    amp   a-z   acute uml circ grave ring cedil slash tilde caron lig quot rsquo   i      1    string         string   preg replace array     a-z0-9  i      -         -    string       return strtolower trim  string   -

User · Answer

Update  The solution below has a  SEO friendlier  version   function hyphenize  string         dict   array           I m         gt   I am            thier       gt   their              Add your own replacements here            return strtolower          preg replace            array       s-          A-Za-z0-9  -                  array   -                      the full cleanString   can be downloaded from http   www unexpectedit com php php-clean-string-of-utf8-chars-convert-to-similar-ascii-char           cleanString                str replace     preg replace can be used to support more complicated replacements                   array keys  dict                     array values  dict                     urldecode  string                                                  function cleanString  text         utf8   array                           u      gt     a                          u       gt     A                        u        gt     I                        u        gt     i                        u        gt     e                        u        gt     E                            u      gt     o                          u       gt     O                        u        gt     u                        u        gt     U                              gt     c                              gt     C                              gt     n                              gt     N                               gt     -      UTF-8 hyphen to  normal  hyphen                             u       gt            Literally a single quote                           u       gt            Double quote                           gt            nonbreaking space  equiv  to 0x160             return preg replace array keys  utf8   array values  utf8    text       The rationale for the above functions  which I find way inefficient - the one below is better  is that a service that shall not be named apparently ran spelling checks and keyword recognition on the URLs   After losing a long time on a customer s paranoias  I found out they were not imagining things after all -- their SEO experts  I am definitely not one  reported that  say  converting  Viaggi Economy Per    to viaggi-economy-peru  behaved better  than viaggi-economy-per  the previous  cleaning  removed UTF8 characters  Bogot   became bogot  Medell  n became medelln and so on    There were also some common misspellings that seemed to influence the results  and the only explanation that made sense to me is that our URL were being unpacked  the words singled out  and used to drive God knows what ranking algorithms  And those algorithms apparently had been fed with UTF8-cleaned strings  so that  Per    became  Peru  instead of  Per    Per  did not match and sort of took it in the neck   In order to both keep UTF8 characters and replace some misspellings  the faster function below became the more accurate     function above   dict needs to be hand tailored  of course   Previous answer  A simple approach      Remove all characters except A-Z  a-z  0-9  dots  hyphens and spaces    Note that the hyphen must go last not to be confused with a range  A-Z     and the dot  NOT being special  I know  My life was a lie   is NOT escaped   str   preg replace     A-Za-z0-9  -          str       Replace sequences of spaces with hyphen  str   preg replace           -    str       The above means  a space  followed by a space repeated zero or more times      should be equivalent to           You may also want to try this alternative   str   preg replace     s      -    str       where  s  means  zero or more whitespaces   a space is not necessarily the    same as a whitespace  just to be sure and include everything   Note that you might have to first urldecode   the URL  since  20 and   both are actually spaces - I mean  if you have  Never 20gonna 20give 20you 20up  you want it to become Never-gonna-give-you-up  not Never20gonna20give20you20up   You might not need it  but I thought I d mention the possibility   So the finished function along with test cases   function hyphenize  string        return         strtolower            preg replace              array      s-          A-Za-z0-9  -                   array  -                       cleanString                urldecode  string                                               print implode   n   array map      function  s                return  s     becomes     hyphenize  s              array       Never 20gonna 20give 20you 20up        I m not the man I was         L  geresse   dit sa majest                Never 20gonna 20give 20you 20up    becomes  never-gonna-give-you-up I m not the man I was              becomes  im-not-the-man-I-was  L  geresse   dit sa majest          becomes  legeresse-dit-sa-majeste   To handle UTF-8 I used a cleanString implementation found online  link broken since  but a stripped down copy with all the not-too-esoteric UTF8 characters is at the beginning of the answer  it s also easy to add more characters to it if you need  that converts UTF8 characters to normal characters  thus preserving the word  look  as much as possible  It could be simplified and wrapped inside the function here for performance   The function above also implements converting to lowercase - but that s a taste  The code to do so has been commented out

User · Answer

This should do what you re looking for   function clean  string        string   str replace       -    string      Replaces all spaces with hyphens      return preg replace     A-Za-z0-9 -          string      Removes special chars      Usage   echo clean  a  bc    de  amp  f g      Will output  abcdef-g  Edit      Hey  just a quick question  how can I prevent multiple hyphens from being next to each other  and have them replaced with just 1    function clean  string        string   str replace       -    string      Replaces all spaces with hyphens      string   preg replace     A-Za-z0-9 -          string      Removes special chars      return preg replace   -      -    string      Replaces multiple hyphens with single one

[php] Remove all special characters from a string

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