PHP: key - Manual

key

danny at dannymendel dot com
12-Apr-2006 08:41


An auto incremental key value function, returning the key value:



<?

function add_key ($value, $array) // returns the key of the value added or existing already within the array

{

    if (is_array ($array))

    {

        if (!in_array ($value, $array))

        {

            ksort ($array);



            end ($array);



            $key = key ($array) + 1;



            $array[$key] = $value;

        }

        else

        {

            $key = array_search ($value, $array);

        }

    }

    else

    {

        $key = 1;



        $array[$key] = $value;

    }

    return $key;

}

?>

php_notes at ionws dot com
10-Oct-2005 04:17


Note that key($array) returns NULL if $array's internal pointer goes past the end of the array.  For example, the following code:



<?php

$arr = array(

    'one' => '1',

    'two' => '2',

    'three' => '3',

    'four' => '4',

    'five' => '5');



for ($i = 0; $i < 10; $i++) {

    var_dump(key($arr));

    next($arr);

}

?>



results in:

string(3) "one"

string(3) "two"

string(5) "three"

string(4) "four"

string(4) "five"

NULL

NULL

NULL

NULL

NULL

Danniel@t h e - police (d'0't) com
22-May-2005 01:55


To get the key name by position from Array:

<?php

$myArray['name1']=3;

$myArray['name2']=2;

$myArray['name3']=1;



echo($myArray[1]);   /* return NULL */

/* isset($myArray[1]) return false;   */

/* is_null($myArray[1]) return true;  */



function KeyName($myArray,$pos) {

   // $pos--; 

   /* uncomment the above line if you */

   /* prefer position to start from 1 */



   if ( ($pos < 0) || ( $pos >= count($myArray) ) )

         return "NULL";  // set this any way you like



   reset($myArray);

   for($i = 0;$i < $pos; $i++) next($myArray);



   return key($myArray);

}



echo KeyName($myArray,1);  // result: name2

echo KeyName($myArray,2);  // result: name3

echo KeyName($myArray,3);  // result: "NULL"

?>



You can get any existing "key name" from array that is located at position $pos gived as second parameter. If no element is defined at given position the function will return the string "NULL".

Danniel@t h e - police (d'0't) com
22-May-2005 01:55


To get the key name by position from Array:

<?php

$myArray['name1']=3;

$myArray['name2']=2;

$myArray['name3']=1;



echo($myArray[1]);   /* return NULL */

/* isset($myArray[1]) return false;   */

/* is_null($myArray[1]) return true;  */



function KeyName($myArray,$pos) {

   // $pos--; 

   /* uncomment the above line if you */

   /* prefer position to start from 1 */



   if ( ($pos < 0) || ( $pos >= count($myArray) ) )

         return "NULL";  // set this any way you like



   reset($myArray);

   for($i = 0;$i < $pos; $i++) next($myArray);



   return key($myArray);

}



echo KeyName($myArray,1);  // result: name2

echo KeyName($myArray,2);  // result: name3

echo KeyName($myArray,3);  // result: "NULL"

?>



You can get any existing "key name" from array that is located at position $pos gived as second parameter. If no element is defined at given position the function will return the string "NULL".

happy dot machine at skynet dot be
06-May-2003 11:20


$tab = array();

$tab[0] = 'php';

$tab[1] = '.';

$tab[2] = 'net';



// you will not enter the while

// $key = 0, while will consider $key as false

reset($tab);

while ($key = key($tab) ) {

echo $tab[$key];

next($tab);

}



// this will

reset($tab);

while (!is_null($key = key($tab) ) ) {

echo $tab[$key];

next($tab);

}



// when key() can't return a 'key', it return NULL

echo var_dump($key);

shimon_d at hotmail dot com
24-Jan-2003 12:39


make array[a][b]

be     array[b][a]



function invertarray($a)

{

 $o=array();

 foreach($a as $k => $aa)

 {

  foreach($aa as $k1 => $v)

  {

   if(!isset($o[$k1]))$o[$k1]=array();

   $o[$k1][$k]=$v;

  }

 }

 return $o;

}

kajetan at kajetan dot nu
04-Jul-2002 01:20


I'm writing a forum and use an array to hold all the smiles. The keys in the array are the characters to write to get a smiley, and the data is the filename, like this

$Smiles[':-)'] = 'smile.gif'



To output all the smileys in a table with 3 columns, I wrote this code:



$the_end = false;



$s = reset($Smiles);

$k = key($Smiles);



while(!$the_end){

    echo '<tr>';

    for($i=0; $i<3; $i++){

        echo '<td>';

        if($the_end) echo '&nbsp;';

        else{

        echo $k.'< br><img src="'. $s .'">';

          $s = next($Smiles);

        if ($s==false) $the_end=true;

        else 

            $k = key($Smiles);

        }

        echo "</td>\n";

    }

    echo "</tr>\n";

}



I had to write a space in the < br> tag in the code above, because the board did a line brake otherwise.

04-Jun-2002 05:13


$input_array = array("FirSt" => 1, "SecOnd" => 4);

print_r(array_change_key_case($input_array, CASE_UPPER));

mkeller at gmx dot de
11-Oct-2001 12:46


In the case key() does not give you back the key(myarray) but "0", try this:


(Try this example without the line containing "end($myarray)" and you see my reason for this post...)





for($i = 0; $i <= 10; $i++) {


        $myarray[] = 'content '.$i;


        end($myarray);


        echo ('<br>key()='.key($myarray).' , content='.$myarray[$i]);


    }

php at snr-graphics dot com
23-Mar-2001 11:50


A Method of Multi-Dimensionalizing an Associative Array (This idea was designed with Graphics (image filenames in mind):





(A quick overview):


While working on a rather large web application, I found that I needed a way to obtain "all" the details on images used by the application, these images (by filename) were stored in the configuration file, in the form of associative arrays.





The following represents an example of how I tool those and converted them into multi-dimensional associative arrays.





<code sample begin>


do {


  $size = getImageSize($path.$myarray[key($myarray)]);


  if ($size[2] == '1') { $size[2] = 'gif'; }


  else if ($size[2] == '2') { $size[2] = 'jpg'; }


  else if ($size[2] == '3') { $size[2] = 'png'; }


  else if ($size[2] == '4') { $size[2] = 'swf'; }


  else { $size[2] = 'UNKNOWN'; }


$myarray[key($myarray)] = Array($myarray[Key($myarray)],$size[0],$size[1],$size[2],$size[3]);


} while (next($myarray));


</end code sample>





The end result is an multi-dim. associative array which contains the values:





$myarray["this"][0] = filename.gif


$myarray["this"][1] = width


$myarray["this"][2] = height


$myarray["this"][3] = type (converted to the file extension.)


$myarray["this"][4] = height=x width=x





This may not be all that impressive to some, but it turned out to be very useful for me, so I thought I'd share, in addition, I think it gives a "very" good example of "a use" for the Key() function.





Frankly, I was quite happy to discover this function, I can't count the number of times I "needed to use the key as a value".





I hope you find this code useful.

key

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