Question

I have array $arr=array("a"=>array("b"=>123))
and I need to do with it something like this:

$a='[a][b]';
echo $arr{$a};

but it doesnt work;

echo $arr[a][b]; – works fine, but it’s not what I need. =(

PHP manual says:

if you write $$a1 then the parser needs to know if you meant to use $a1 as a variable, or if you wanted $$a as the variable and then the 1 index from that variable. The syntax for resolving this ambiguity is: ${$a1} for the first case and ${$a}1 for the second. >> php manual

but “echo ${$a};” and “echo $arr{$a};” and all the other variations output nothing.

UPDATE

in short, I need to delete an element of assotiative array via form.
For example, I have $a=array(‘abc’=>’def’);
and html form

<form><input name="deleteIT" value="[abc]"></form>

So, after submitting I want to delete from $a variable $deleteIT value.

Answer 1

Is this close enough to what you need?

$a = "a,b";
list( $i, $j ) = explode( ",", $a );
echo $arr[$i][$j];

---

Addendum: The answer above will work if the array $arr always has exactly two levels. If it might have more (or less), something like the following could work:

function array_get_nested ( $array, $keys ) {
    $value = $array;
    foreach ( $keys as $index ) {
        $value = $value[ $index ];
    }
    return $value;
}

The function above takes two arrays as arguments: one containing the value we want, and another listing the keys we need to locate it in the first array. For example, if we have an array like this:

$arr = array( "a" => array( "b" => array( "c" => 123 ) ) );

then

echo array_get_nested( $arr, array( "a", "b", "c" ) );

would print 123.

Converting string keys into an array suitable for the second argument to array_get_nested() depends on how the keys are formatted, but it could be as simple as calling explode() with a suitable delimiter. For example, the last line of code above could be rewritten as:

$k = "a,b,c";
echo array_get_nested( $arr, explode( ",", $k ) );

To modify nested arrays, we can use a similar function:

function array_set_nested ( &$array, $keys, $value ) {
    $ref =& $array;
    foreach ( $keys as $index ) {
        $ref =& $ref[ $index ];
    }
    $ref = $value;
}

Note that PHP conveniently “autovivifies” arrays for us, so we can, for example, take a previously undefined variable $foo and turn it into a three-level nested array simply with:

array_set_nested( $foo, array( "a", "b", "c" ), 123 );