How to use php serialize and unserialize

Question

My problem is very basic   I did not find any example to meet my needs as to what exactly serialize   and unserialize   mean in php  They just give an example - serialize an array and show an output in an unexplained format  It is really hard to understand the basic concept going through their jargon   EDIT    lt  php   a  array   1    gt   elem 1    2   gt   elem 2    3   gt   elem 3    print r  a   echo    lt br gt  lt  br gt      b serialize  a   print r  b      gt    output   Array    1    gt  elem 1  2    gt  elem 2  3    gt  elem 3     a 3  i 1 s 6  elem 1  i 2 s 6  elem 2  i 3 s 7   elem 3      I cannot understand the second output  Besides that  can anyone give an example of a situation that I need to serialize a php array before using it

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From http   php net manual en function serialize php       Generates a storable representation of a value    This is useful for storing or passing PHP values around without losing their type and structure     Essentially  it takes a php array or object and converts it to a string  which you can then transmit or store as you see fit    Unserialize is used to convert the string back to an object

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Most storage mediums can store string types  They can not directly store a PHP data structure such as an array or object  and they shouldn t  as that would couple the data storage medium with PHP   Instead  serialize   allows you to store one of these structs as a string  It can be de-serialised from its string representation with unserialize     If you are familiar with json encode   and json decode    and JSON in general   the concept is similar

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When you want to make your php value storable  you have to turn it to be a string value  that is what serialize   does  And unserialize   does the reverse thing

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Basically  when you serialize arrays or objects you simply turn it to a valid string format so that you can easily store them outside of the php script    Use serialize to save the state of an object in database  lets take the User class as an example  Next unserialize the data to load the previous state back to the object  methods are not serializer you need to include object class to be able to use it    user personalization     Note for object you should use  magic   sleep and   wakeup methods    sleep is called by serialize    A sleep method will return an array of the values from the object that you want to persist     wakeup is called by unserialize    A wakeup method should take the unserialized values and initialize them in them in the object   For passing data between php and js you would use json encode to turn php array to valid json format  Or other way round - use JSON parese   to convert a output data  string  into valid json object  You would want to do that to make use of local storage   offline data access

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A PHP array or object or other complex data structure cannot be transported or stored or otherwise used outside of a running PHP script  If you want to persist such a complex data structure beyond a single run of a script  you need to serialize it  That just means to put the structure into a  lower common denominator  that can be handled by things other than PHP  like databases  text files  sockets  The standard PHP function serialize is just a format to express such a thing  it serializes a data structure into a string representation that s unique to PHP and can be reversed into a PHP object using unserialize  There are many other formats though  like JSON or XML     Take for example this common problem   How do I pass a PHP array to Javascript   PHP and Javascript can only communicate via strings  You can pass the string  foo  very easily to Javascript  You can pass the number 1 very easily to Javascript  You can pass the boolean values true and false easily to Javascript  But how do you pass this array to Javascript   Array    1    gt  elem 1  2    gt  elem 2  3    gt  elem 3      The answer is serialization  In case of PHP Javascript  JSON is actually the better serialization format     1    elem 1   2    elem 2   3    elem 3      Javascript can easily reverse this into an actual Javascript array   This is just as valid a representation of the same data structure though   a 3  i 1 s 6  elem 1  i 2 s 6  elem 2  i 3 s 7   elem 3      But pretty much only PHP uses it  there s little support for this format anywhere else  This is very common and well supported as well though    lt array gt       lt element key  1  gt elem 1 lt  element gt       lt element key  2  gt elem 2 lt  element gt       lt element key  3  gt elem 3 lt  element gt   lt  array gt    There are many situations where you need to pass complex data structures around as strings  Serialization  representing arbitrary data structures as strings  solves how to do this

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PHP serialize   unserialize   usage   http   freeonlinetools24 com serialize  echo   lt pre gt       say you have an array something like this   multidimentional array  array      array          array  rose   1 25  15           array  daisy   0 75  25           array  orchid   4  7                 array          array  rose   1 25  15           array  daisy   0 75  25           array  orchid   5  7                 array          array  rose   1 25  15           array  daisy   0 75  25           array  orchid   8  7                serialize   serialized array serialize  multidimentional array   print r  serialized array     Which gives you an output something like this   a 3  i 0 a 3  i 0 a 3  i 0 s 4  rose  i 1 d 1 25 i 2 i 15  i 1 a 3  i 0 s 5  daisy  i 1 d 0 75 i 2 i 25  i 2 a 3  i 0 s 6  orchid  i 1 i 4 i 2 i 7   i 1 a 3  i 0 a 3  i 0 s 4  rose  i 1 d 1 25 i 2 i 15  i 1 a 3  i 0 s 5  daisy  i 1 d 0 75 i 2 i 25  i 2 a 3  i 0 s 6  orchid  i 1 i 5 i 2 i 7   i 2 a 3  i 0 a 3  i 0 s 4  rose  i 1 d 1 25 i 2 i 15  i 1 a 3  i 0 s 5  daisy  i 1 d 0 75 i 2 i 25  i 2 a 3  i 0 s 6  orchid  i 1 i 8 i 2 i 7       again if you want to get the original array back just use PHP unserialize   function    original array unserialize  serialized array   var export  original array     I hope this will help

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preg match all           i    string   matches   foreach   matches 0  as  i   gt   match   matches  i    trim  match

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lt  php  a  array  1   2   3    print r  a    b serialize  a   echo  b   c unserialize  b   print r  c     Run this program its echo the output  a 3  i 0 s 1  1  i 1 s 1  2  i 2 s 1  3       here a size of array i count of array number s size of array values  you can use serialize to store array of data in database and can retrieve and UN-serialize data to use

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Yes  I can  Assume we need to track your system means In your system has more than one admin and subadmin  All of these can insert or update or edit any information Later you need to know who make this change  For solving this problem you need serialize       Explain   Create a table named history which stores all changes  Each time there is a change insert a new row in this table  It might have this fields     history id target table name of the table   target id  ID of the saved entry  create edit change data  serialized data of the saved row  date    I hope this will help you

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Please  please  please  DO NOT serialize data and place it into your database  Serialize can be used that way  but that s missing the point of a relational database and the datatypes inherent in your database engine  Doing this makes data in your database non-portable  difficult to read  and can complicate queries  If you want your application to be portable to other languages  like let s say you find that you want to use Java for some portion of your app that it makes sense to use Java in  serialization will become a pain in the buttocks  You should always be able to query and modify data in the database without using a third party intermediary tool to manipulate data to be inserted    it makes really difficult to maintain code  code with portability issues  and data that is it more difficult to migrate to other RDMS systems  new schema  etc  It also has the added disadvantage of making it messy to search your database based on one of the fields that you ve serialized    That s not to say serialize   is useless  It s not    A good place to use it may be a cache file that contains the result of a data intensive operation  for instance  There are tons of others    Just don t abuse serialize because the next guy who comes along will have a maintenance or migration nightmare   A good example of serialize   and unserialize   could be like this    posts   base64 encode serialize   POST    header  Location    SERVER REQUEST URI  x  posts      Unserialize on the page  if   GET  x            unpack serialize and encoded URL      POST   unserialize base64 decode   GET  x

[php] How to use php serialize() and unserialize()

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