Increase Array Dimension Dynamically

keenlearner

Is there a way that we can increase the array dimension dynamically (during the runtime) ?
like

$a = array();

// May be using for loop
for($i=0; $i < 5; $i++)

$a[0];
$a[0][0];
$a[0][0][0];
$a[0][0][0][0];
$a[0][0][0][0][0];

But not sure how can I accomplished that, or maybe is there other way which has the same concept as this dynamic array dimension resizing ? Thanks

laserlight

What exactly are you trying to do? PHP arrays (and variables in general) are not statically typed, nor are they of a fixed size or dimension (unless you treat them as such).

keenlearner

Thanks for your reply,
The codes that I showed is what we have typed manually,but I want to resize the dimension dynamically, any dimension which depends on the program execution.

Here is the pseudo code :

if (I_WANT_5_DIMENSION_ARRAY)
Make array of 5 dimension;
else if (I_WANT_6_DIMENSION_ARRAY)
Make array of 6 dimension

and so on.

laserlight

There is no need for that. Just create an array, and then add arrays as elements to that array as needed.

The thing is, what are you actually trying to do? Not the details, but the big picture. In other words, why do you want to do this?

keenlearner

Found the solutions, thanks....

<?php

$depth = 5;
eval('$array = '.str_repeat('array(', $depth).str_repeat(')', $depth).';');
print_r($array);

?>

Output

Array
(
[0] => Array
(
[0] => Array
(
[0] => Array
(
[0] => Array
(
)
)
)
)
)

laserlight

sigh

The reason why I am asking is that there may be better ways of solving your problem.

Creating an array right away with 5 dimensions is not necessarily the best approach: the result would not be a true 5-D array since you can add elements anywhere in between.

Yes, you have found a solution, but even then it is horrible: use str_repeat() with eval()? Sounds like a candidate for submission to worsethanfailure.com, or some PHP code obfuscation contest.

A far simpler solution is:

$depth = 5;
$array = array();
for ($i = 1; $i < $depth; ++$i) {
    $array = array($array);
}

keenlearner

Thanks for trying to help me, but wait... I am writing the thing that you want to know what I am doing.

keenlearner

Actually you are right, I am so blur today, I forgot that there is not a need to increase the array dimension, because the array dimension will be automatically increased when I insert array into the array. It takes a bit of writing but here is exactly what I am trying to do , maybe you can help me to improve, I am trying to make an algebra calculator , such as if I had an equation

$str = '4 + r - 5 = 8';

it should give the result of "r" as 9, I have done this by inputing each character into $segment array in this way;

$segment = array();
for($i=0; $i < strlen($str); $i++)
    $segment[$i] = $str[$i];

Then I moved all the numbers at the left hand side to the right hand side which is after the equal operator and also change the number sign from positive to negative and vice versa. The number that has been moved to the right hand side is stored by appending into the $segment array.

The equation will look like this now which is stored in the $segment array.

4 + r - 5 = 8 - 4 + 5;

$rhs = '';
for($j=$equalSignIndex+1; $i< sizeof($segment); $i++){
    $rhs =. $segment[$i]; // Get the right hand side numbers which is 8- 4 + 5
}

return eval("return $rhs;"); // gives the result of 9

The above one might have better way of doing it. But what I am having a problem which is the parentheses, such as below

((2 + 1) * t ) + 5 = 8;

I was thinking to store the character in parentheses into $segment array in multi dimension like

$segment[0] = '((2 + 1) * t )';
$segment[0][0] = '(2 + 1)';
$segment[0][1] = '*';
$segment[0][2] = 't';
$segment[1] = '+' // We have come out from parentheses so we want to store in new index
$segment[2] = '5';
$segment[3] = '=';
$segment[4] = '8';

The use of multi dimension array for me is to let me be able to keep track of the position inside the parentheses.So that I know the very first thing to do is to evaluate those from the innermost parentheses which has the biggest array dimension such as $segment[0][0] which gives result of 3 and stored it again in $segment[0][0]. And the rest of evaluation will goes slightly different from the previous equation to get the result of t. My explanation might be hard to be understood and also might have silly way of doing it, but hope you can understand and help to improve, thank you.