PHP array delete by value not key

Question

I have a PHP array as follows    messages    312  401  1599  3          I want to delete the element containing the value  del val  for example   del val 401   but I don t know its key  This might help  each value can only be there once   I m looking for the simplest function to perform this task  please

User · Answer

A one-liner using the or operator     key   array search  del val   messages       false or unset  messages  key

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I think the simplest way would be to use a function with a foreach loop     This functions deletes the elements of an array  original that are equivalent to the value  del val   The function works by reference  which means that the actual array used as parameter will be modified   function delete value  amp  original   del val          make a copy of the original  to avoid problems of modifying an array that is being currently iterated through      copy    original      foreach   original as  key   gt   value                  for each value evaluate if it is equivalent to the one to be deleted  and if it is capture its key name          if  del val      value   del key      key               If there was a value found  delete all its instances     if  del key     null                foreach   del key as  dk i                        unset  original  dk i                         optional reordering of the keys  WARNING  only use it with arrays with numeric indexes                      copy    original           original   array            foreach   copy as  value                 original      value                                  the value was found and deleted         return true               The value was not found  nothing was deleted     return false       original   array 0 1 2 3 4 5 6 7 4    del val   4  var dump  original   delete value  original   del val   var dump  original     Output will be   array 9       0   gt    int 0     1   gt    int 1     2   gt    int 2     3   gt    int 3     4   gt    int 4     5   gt    int 5     6   gt    int 6     7   gt    int 7     8   gt    int 4    array 7       0   gt    int 0     1   gt    int 1     2   gt    int 2     3   gt    int 3     5   gt    int 5     6   gt    int 6     7   gt    int 7

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If you don t know its key it means it doesn t matter   You could place the value as the key  it means it will instantly find the value  Better than using searching in all elements over and over again    messages array        messages 312    312       messages 401    401      messages 1599    1599      messages 3    3       unset  messages 3       no search needed

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Or simply  manual way   foreach   array as  key   gt   value       if   value     target value            unset  array  key              This is the safest of them because you have full control on your array

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With PHP 7 4 using arrow functions    messages   array filter  messages  fn   m    gt   m     del val     To keep it a non-associative array wrap it with array values      messages   array values array filter  messages  fn   m    gt   m     del val

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Using array search   and unset  try the following   if    key   array search  del val   messages       false        unset  messages  key        array search   returns the key of the element it finds  which can be used to remove that element from the original array using unset    It will return FALSE on failure  however it can return a false-y value on success  your key may be 0 for example   which is why the strict comparison     operator is used   The if   statement will check whether array search   returned a value  and will only perform an action if it did

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One interesting way is by using array keys     foreach  array keys  messages  401  true  as  key        unset  messages  key        The array keys   function takes two additional parameters to return only keys for a particular value and whether strict checking is required  i e  using     for comparison    This can also remove multiple array items with the same value  e g   1  2  3  3  4

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The accepted answer converts the array to associative array  so  if you would like to keep it as a non-associative array with the accepted answer  you may have to use array values too   if   key   array search  del val   messages       false        unset  messages  key         arr   array values  messages       The reference is here

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function array remove by value  array   value        return array values array diff  array  array  value         array   array 312  401  1599  3     newarray   array remove by value  array  401    print r  newarray     Output  Array    0    gt  312  1    gt  1599  2    gt  3

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I know this is not efficient at all but is simple  intuitive and easy to read  So if someone is looking for a not so fancy solution which can be extended to work with more values  or more specific conditions    here is a simple code    result   array     del value   401     del values   array     all the values you don t wont    foreach  arr as  key   gt  value       if   value      del value            result  key     value               if  in array  value   del values               result  key     value                 if  this- gt validete  value                 result  key     value             return  result

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To delete multiple values try this one   while    key   array search  del val   messages       false         unset  messages  key

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As per your requirement  each value can only be there for once  if you are just interested in keeping unique values in your array  then the array unique   might be what you are looking for   Input    input   array 4   4    3   4  3   3     result   array unique  input   var dump  result     Result   array 2       0    gt  int 4     2    gt  string 1   3

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If you know for definite that your array will contain only one element with that value  you can do   key   array search  del val   array   if  false      key        unset  array  key        If  however  your value might occur more than once in your array  you could do this   array   array filter  array  function  e  use   del val        return   e      del val         Note  The second option only works for PHP5 3  with Closures

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The Best way is array splice  array splice  array  array search 58   array    1     Reason for Best is here at http   www programmerinterview com index php php-questions how-to-delete-an-element-from-an-array-in-php

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Borrowed the logic of underscore JS   reject and created two functions  people prefer functions     array reject value  This function is simply rejecting the value specified  also works for PHP4 5 7   function array reject value array  amp  arrayToFilter   deleteValue         filteredArray   array         foreach   arrayToFilter as  key   gt   value            if   value      deleteValue                 filteredArray      value                       return  filteredArray      array reject  This function is simply rejecting the callable method  works for PHP   5 3   function array reject array  amp  arrayToFilter  callable  rejectCallback          filteredArray   array         foreach   arrayToFilter as  key   gt   value            if    rejectCallback  value   key                  filteredArray      value                       return  filteredArray      So in our current example we can use the above functions as follows    messages    312  401  1599  3  6    messages   array reject value  messages  401     or even better   as this give us a better syntax to use like the array filter one    messages    312  401  1599  3  6    messages   array reject  messages  function   value        return  value     401        The above can be used for more complicated stuff like let s say we would like to remove all the values that are greater or equal to 401 we could simply do this    messages    312  401  1599  3  6    greaterOrEqualThan   401   messages   array reject  messages  function   value  use  greaterOrEqualThan       return  value  gt    greaterOrEqualThan

User · Answer

Well  deleting an element from array is basically just set difference with one element   array diff   312  401  15  401  3    401       removing 401 returns  312  15  3    It generalizes nicely  you can remove as many elements as you like at the same time  if you want   Disclaimer  Note that my solution produces a new copy of the array while keeping the old one intact in contrast to the accepted answer which mutates  Pick the one you need

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you can do   unset  messages array flip  messages   401        Explanation  Delete the element that has the key 401 after flipping the array

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fields   array flip  fields   unset  fields  myvalue      fields   array flip  fields

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here is one simple but understandable solution   messagesFiltered       foreach   messages as  message        if  401     message             messagesFiltered      message           messages    messagesFiltered

[php] PHP array delete by value (not key)

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