[php] php: how to get associative array key from numeric index?

If I have:

$array = array( 'one' =>'value', 'two' => 'value2' );

how do I get the string one back from $array[1] ?

Expanding on Ram Dane's answer, the key function is an alternative way to get the key of the current index of the array. You can create the following function,

    function get_key($array, $index){
      $idx=0;
      while($idx!=$index  && next($array)) $idx++;
      if($idx==$index) return key($array);
      else return '';
    }

$array = array( 'one' =>'value', 'two' => 'value2' );

$allKeys = array_keys($array);
echo $allKeys[0];

Which will output:

one

You might do it this way:

function asoccArrayValueWithNumKey(&$arr, $key) {
   if (!(count($arr) > $key)) return false;
   reset($array);
   $aux   = -1;
   $found = false;
   while (($auxKey = key($array)) && !$found) {
      $aux++;
      $found = ($aux == $key);
   }
   if ($found) return $array[$auxKey];
   else return false;
}

$val = asoccArrayValueWithNumKey($array, 0);
$val = asoccArrayValueWithNumKey($array, 1);
etc...

Haven't tryed the code, but i'm pretty sure it will work.

Good luck!

If you only plan to work with one key in particular, you may accomplish this with a single line without having to store an array for all of the keys:

echo array_keys($array)[$i];

If it is the first element, i.e. $array[0], you can try:

echo key($array);

If it is the second element, i.e. $array[1], you can try:

next($array);
echo key($array);

I think this method is should be used when required element is the first, second or at most third element of the array. For other cases, loops should be used otherwise code readability decreases.

The key function helped me and is very simple:

The key() function simply returns the key of the array element that's currently being pointed to by the internal pointer. It does not move the pointer in any way. If the internal pointer points beyond the end of the elements list or the array is empty, key() returns NULL.

Example:

<?php
    $array = array(
        'fruit1' => 'apple',
        'fruit2' => 'orange',
        'fruit3' => 'grape',
        'fruit4' => 'apple',
        'fruit5' => 'apple');

    // this cycle echoes all associative array
    // key where value equals "apple"
    while ($fruit_name = current($array)) {
        if ($fruit_name == 'apple') {
            echo key($array).'<br />';
        }
        next($array);
    }
?>

The above example will output:

fruit1<br />
fruit4<br />
fruit5<br />

$array = array( 'one' =>'value', 'two' => 'value2' );
$keys  = array_keys($array);
echo $keys[0]; // one
echo $keys[1]; // two

Or if you need it in a loop

foreach ($array as $key => $value)
{
    echo $key . ':' . $value . "\n";
}
//Result: 
//one:value
//two:value2