What are the ways to iterate an array in PHP (without foreach)?

Question

Before I am censured by the question, notice beforehand that the purpose of it is simply to level curiosity. I know that the foreach is the most suitable means for this.

But I would like to know the following:

What are the ways to iterate with a array in PHP, without using foreach, so that you can access índice and the valor (as in the foreach)?

I would like to see examples with for, while or even functions.

I’ll leave a array for response model:

$array = array(
    'stack' => 'Overflow',
    'linguagem' => 'Português',
    'tags' => array('PHP', 'Iteração', 'Array')
);

I need the interaction to happen this way (exemplifying with foreach):

foreach($array as $indice => $valor)
{
   var_dump($indice, $valor);
}

Heed: The only case not accepted for iteration with for is that of $i++, since it is a plastered way and only serves to array numerically indexed.

Answer 1

Being also a beginner, I became interested in the question and found an interesting article about it.

Here’s a solution according to the article.

$array = array(
    'stack' => 'Overflow',
    'linguagem' => 'Português',
    'tags' => array('PHP', 'Iteração', 'Array')
);

$keys = array_keys($array);

$size = count($array);

for ($i = 0; $i < $size; $i++) {
    $key   = $keys[$i];
    $value = $array[$key];

    echo $value;

}

See the code working on IDEONE

Ref: PHP Internals: When does foreach copy?

Answer 2

It is also possible to iterate an array using the functions, array_walk() or array_walk_recursive(), the first argument is the array you want to iterate, the second is the function that must be applied to all elements, this function can be an already declared or an anonymous one(clousere)

$array = array(
    'stack' => 'Overflow',
    'linguagem' => 'Português',
    'tags' => array('PHP', 'Iteração', 'Array')
);

array_walk($array, function($v, $k) { 
    var_dump($v, $k);
});

In the case of array_walk_recursive, it will iterate with the elements of array recursively.

Behold:

array_walk_recursive($array, function ($value, $key) {
    var_dump($value, $key);
});

Upshot:

string(8) "Overflow"
string(5) "stack"
string(10) "Português"
string(9) "linguagem"
string(3) "PHP"
int(0)
string(10) "Iteração"
int(1)
string(5) "Array"
int(2)

Example in IDEONE

Example - ideone

Answer 3

I couldn’t help myself without having to give my stick around

Another good way to make this iteration of a array, without the foreach, would be with a while, iterating over an instance of ArrayIterator.

Behold:

 $it = new ArrayIterator($array);

 while ($it->valid()) {

    $indice = $it->key();

    $valor = $it->current();

    $it->next();
 }

Just remembering that to make another iteration, it would be necessary to use the method rewind to return to the pointer at the beginning.

$it->rewind(); // Após o while

Answer 4

Still speaking of objects we could do so too:

$array = array(
    'stack' => 'Overflow',
    'linguagem' => 'Português',
    'tags' => array('PHP', 'Iteração', 'Array')
);

$arrayobject = new ArrayObject($array);

$iterator = $arrayobject->getIterator();

while($iterator->valid()) {
    echo $iterator->key() . ' => ' . $iterator->current() . "\n";

    $iterator->next();
}

Important to remember is that we have to use the method next within the while to move to the next element and thus avoid a infinite loop.

I’d fall for your own response concerning the ArrayIterator()

Answer 5

You can use the array_walk:

$array = array(
    'stack' => 'Overflow',
    'linguagem' => 'Português',
    'tags' => array('PHP', 'Iteração', 'Array')
);

array_walk($array, function ($value, $key){
    var_dump($key, $value);
});

If the index is irrelevant, array_map can be used

$array = array(
    'stack' => 'Overflow',
    'linguagem' => 'Português',
    'tags' => array('PHP', 'Iteração', 'Array')
);

array_map(function($value)
{
    var_dump($value);
}, $array); 

Answer 6

Another way to do this is by using the function each.

She picks up the current pointer from array and turns into another array, containing the value of the index and the value of the index array. Then it passes to the next element of the array.

Example;

each($array);

Upshot:

Array
(
    [1] => Portugus
    [value] => Portugus
    [0] => linguagem
    [key] => linguagem
)

See that it returns a key called value and another as a numerical index. This is so that it is possible to use this function with the list.

So we can do this:

while (list($key, $value) = each($array)) {
    var_dump($key, $value);
}

We can also use (oddly) a for for that reason:

for (; list($key, $value) = each($array); ) {
      var_dump($key, $value);
}

Answer 7

You can build a Patterns design interaction, as the example below, which is based on PHP Iterator ( http://php.net/manual/en/class.iterator.php ):

 <?php

   //entrada de elementos
    $myCollection = [
        new stdClass(),
        new stdClass(),
        new stdClass(),
        new stdClass(),
    ];
     /**
     * :::: Iterator Interface 
     *
     * @author ivan-ferrer
     */
    interface MyIteratorInterface
    {
        public function current();
        public function rewind();
        public function next();
        public function key();
        public function valid();
    }

    // Estruturais, Comportamentais e Criacionais
    // PHP Iterator

    class PHPIterator implements Iterator, MyIteratorInterface
    {
        private $collection = [];
        private $key        = 0;

        public function __construct(array $collection = [])
        {
            $this->collection = $collection;
        }

        public function rewind()
        {
            $this->key = 0;
        }


        public function current()
        {
            return $this->collection[$this->key];
        }

        public function key()
        {
            return $this->key;
        }

        public function next()
        {
            ++$this->key;
        }


        public function valid()
        {
            return isset($this->collection[$this->key]);
        }
    }

    $phpIterator = new PHPIterator($myCollection);

    echo "-----------------while--------------------\n";
    $phpIterator->rewind();

    while ($phpIterator->valid()) {
        var_dump($phpIterator->current());
        $phpIterator->next();
    }

    echo "-------------------for--------------------\n";


    for ($phpIterator->rewind(); $phpIterator->valid(); $phpIterator->next()) {
        var_dump($phpIterator->current());
    }


    echo "------------------foreach-----------------\n";

    foreach ($phpIterator as $key => $object) {
        var_dump($object);
    }

There are also several other ways to make a iterator: http://php.net/manual/en/spl.iterators.php

Answer 8

It is possible to treat it as an object like this:

$array = array(
    'stack' => 'Overflow',
    'linguagem' => 'Português',
    'tags' => array('PHP', 'Iteração', 'Array')
);


$A = $array;
while(!is_null(key($A))) {
  var_dump(current($A));
  next($A);
}

http://php.net/manual/en/language.oop5.iterations.php

Answer 9

In fact, a loop for does not work well with arrays with non-numeric indexes, but it is possible to circumvent this if "reset" as Keys but are not important, with array_values.

$array = array(
    'stack' => 'Overflow',
    'linguagem' => 'Português',
    'tags' => array('PHP', 'Iteração', 'Array')
);

$numericArray = array_values($array);

$count = count($numericArray);

for ($i = 0; $i < $count; $i++){
    var_dump($numericArray[$i]);
}

Answer 10

Okay, just fuck with me, here’s my answer:

print_r( $array );

This iterates and already shows on the screen at once, both keys and values.

And best of all, it works on arrays multi-level ;)

^{_{Okay, there’s no way to leverage the data for a lot of different things, but if it’s just for show, print_r comes with "complete package".}}

Answer 11

It was said in the previous answer that array_map disregard the index.

However, there is another very interesting way. It is using array_map, with multipos parameters. Thus, we can pass an array with keys, and the other, to values.

Thus:

$array = array('nome' => 'wallace', 'idade' => 25);

$map = function ($value, $key)
{
   echo "$key => $value";
}

array_map($map, $array, array_keys($array));

Related: What is the purpose of array_map to accept infinite array parameters, after callback?

Answer 12

Using do ... while:

    do
    {
        $cliente = current($dados_teste); // acessa item atual com "current"
        $tabela.= $cliente['nome'] .'-'. $cliente['idade']; // usa os dados
    }            
    while(next($dados_teste)!==false); // avança o ponteiro com "next"

Sample code:

<?php

    $dados_teste = array(
                            array(
                                    'nome'=>'Pedro',
                                    'idade'=>'45',
                                    'uf'=>'RJ'
                                ),

                            array(
                                    'nome'=>'Maria',
                                    'idade'=>'30',
                                    'uf'=>'RJ'
                                ),    

                            array(
                                    'nome'=>'Miguel',
                                    'idade'=>'28',
                                    'uf'=>'MG'
                                ),    

                            array(
                                    'nome'=>'Paulo',
                                    'idade'=>'52',
                                    'uf'=>'SP'
                                ),                            
                        );


    $tabela = '<table>
        <tr><th>Nome</th><th>Idade</th><th>UF</th></tr>';

    do
    {
        $cliente = current($dados_teste);

        $tabela.= '
        <tr><td>'.$cliente['nome'] .'</td><td>'. $cliente['idade'] .'</td><td>'.  $cliente['uf'] .'</td></tr>';
    }            
    while(next($dados_teste)!==false);    

    $tabela.='
    </table>';   

?><!DOCTYPE HTML>
<html>
<head>
    <title>Exemplo Iterando array com Do...While</title>
    <style>
        table {border-collapse: collapse; }
        th,td { border:1px solid #777; padding:10px; }
    </style>
</head>
<body>
    <?php echo $tabela; ?>

</body>
</html>

Output:

    <!DOCTYPE HTML>
    <html>
    <head>
        <title>Exemplo Iterando array com Do...While</title>
        <style>
            table {border-collapse: collapse; }
            th,td { border:1px solid #777; padding:10px; }
        </style>
    </head>
    <body>
        <table>
            <tr><th>Nome</th><th>Idade</th><th>UF</th></tr>
            <tr><td>Pedro</td><td>45</td><td>RJ</td></tr>
            <tr><td>Maria</td><td>30</td><td>RJ</td></tr>
            <tr><td>Miguel</td><td>28</td><td>MG</td></tr>
            <tr><td>Paulo</td><td>52</td><td>SP</td></tr>
        </table>
    </body>
    </html>