How to check if variable is array or something array-like

Question

I want to use a foreach loop with a variable  but this variable can be many different types  NULL for example   So before foreach I test it   if is array  var      foreach  var as       But I realized that it can also be a class that implements Iterator interface  Maybe I am blind but how to check whether the class implements interface  Is there something like is a function or inherits operator  I found class implements  I can use it  but maybe there is something simpler   And second  more important  I suppose this function exist  would be enough to check if the variable is array or  implements Iterator interface  or should I test for something more

User · Answer

You can check instance of Traversable with a simple function  This would work for all this of Iterator because Iterator extends Traversable  function canLoop  mixed        return is array  mixed      mixed instanceof Traversable   true   false

User · Answer

lt  php  var   new ArrayIterator     var dump is array  var     var instanceof ArrayIterator      returns bool false  or bool true

User · Answer

foreach can handle arrays and objects  You can check this with    can foreach   is array  var     is object  var   if   can foreach        foreach   var as         You don t need to specifically check for Traversable as others have hinted it in their answers  because all objects - like all arrays - are traversable in PHP   More technically      foreach works with all kinds of traversables  i e  with arrays  with plain objects  where the accessible properties are traversed  and Traversable objects  or rather objects that define the internal get iterator handler       source   Simply said in common PHP programming  whenever a variable is    an array an object   and is not   NULL a resource a scalar   you can use foreach on it

User · Answer

Since PHP 7 1 there is a pseudo-type iterable for exactly this purpose  Type-hinting iterable accepts any array as well as any implementation of the Traversable interface   PHP 7 1 also introduced the function is iterable    For older versions  see other answers here for accomplishing the equivalent type enforcement without the newer built-in features   Fair play  As BlackHole pointed out  this question appears to be a duplicate of Iterable objects and array type hinting  and his or her answer goes into further detail than mine

User · Answer

Functions   lt  php         Is Array      param mixed  x     return bool     function isArray  x    bool     return  isAssociative  x             Is Associative Array      param mixed  x     return bool     function isAssociative  x    bool     if   is array  array         return false         i   count  array     while   i  gt  0        if   isset  array -- i            return true              return false      Example   lt  php   arr      foo    bar      obj      foo    gt   bar      var dump isAssociative  arr      bool false   var dump isAssociative  obj      bool true   var dump isArray  obj      bool false   var dump isArray  arr      bool true

User · Answer

If you are using foreach inside a function and you are expecting an array or a Traversable object you can type hint that function with    function myFunction array  a  function myFunction Traversable    If you are not using foreach inside a function or you are expecting both you can simply use this construct to check if you can iterate over the variable   if  is array  a  or   a instanceof Traversable

User · Answer

PHP 7 1 0 has introduced the iterable pseudo-type and the is iterable   function  which is specially designed for such a purpose   This       proposes a new iterable pseudo-type  This type is analogous to callable  accepting multiple types instead of one single type  iterable accepts any array or object implementing Traversable  Both of these types are iterable using foreach and can be used with yield from within a generator   function foo iterable  iterable        foreach   iterable as  value                             This       also adds a function is iterable   that returns a boolean  true if a value is iterable and will be accepted by the iterable pseudo-type  false for other values   var dump is iterable  1  2  3        bool true  var dump is iterable new ArrayIterator  1  2  3         bool true  var dump is iterable  function      yield 1             bool true  var dump is iterable 1       bool false  var dump is iterable new stdClass         bool false   You can also use the function is array  var  to check if the passed variable is an array   lt  php     var dump  is array array          true     var dump  is array array 1  2  3         true     var dump  is array   SERVER        true   gt   Read more in How to check if a variable is an array in PHP

[php] How to check if variable is array?... or something array-like

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