Variable variable OK! But with ARRAY indexes - problem!

[muTual]

It would be very useful for me if I could get values of multidimensional array using:
- name of array from string variable
- sequence of indexes of array from string variable

Code: Select all

$arr[1][2]="correct array value";

$arr_name="arr";
$arr_idx="[1][2]";


Next code works, but it's not I want get:

Code: Select all

echo 'example 1 = ('.${$arr_name}[1][2].')';


What I want is:

Code: Select all

// it doesn't return value:
echo 'example 2 = ('.${$arr_name}[$arr_idx].')';
// it doesn't return value too:
echo 'example 3 = ('.${$arr_name.$arr_idx}.')';


Somebody knows how to achieve effect returning correct value? I need help.
Thanks.

[DoppyNL]

If you want to acces a variable with the name wich is stored in another variable, you will have to do this like this:

Code: Select all

$varname = 'variable_name';
$variable_name = 'Greetings Eartlings';
print($$varname);


this will output:

Greetings Earthlings

This is no different when using arrays or not.



When you want to use a variable to acces a specific index in you're array you can do that as follows:

Code: Select all

$my_array[12] = 'Greetings Eartlings';
$array_index = 12;
print($my_array[$array_index]);


this wil output:

Greetings Eartlings

This can be done with strings as well, works the same.


What you can't do is using 1 variable to acces a multi-dymension array:

Code: Select all

$my_array[12][15] = 'Greetings Eartlings';
$my_index = "[12][15]"
print($my_array[$my_index]); //-- or any variant

will not work!
You will have to use 2 variables to acces both indexes seperately.
Like this:

Code: Select all

$my_array[12][15] = 'Greetings Eartlings';
$my_index1 = 12;
$my_index2 = 15;
print($my_array[$my_index1][$my_index2];

will output:

Greetings Eartlings

Hope this helps.

Greetz Daan

[muTual]

Thx for answer. I know that your examples work, but my $arr_idx variable is not always "two-dimension", it may be:

Code: Select all

$arr_idx="[1][2]";
//or
$arr_idx="[3]";
//or
$arr_idx="[2][3][1]";
//and so on...

$arr_idx is depended on my previous source code.
I'm curious if php compiler can interpret (in some way) array name jointly with indexes string...
Can I do this in some other way?
Thanks for other answers in advance.

Michael

[DoppyNL]

As far as I know you can't acces a multi-level array like that (but I could be wrong).

a possible solution could be this:

Code: Select all

$your_array_name[1][3][12] = 'Greetings Earthlings';
$indexes = '[1][3][12]';
$tempvar = 'print($your_array_name' . $indexes . ');';
eval($tempvar);

$tempvar equals to this:

print($your_array_name[1][3][12]);

and the output is this:

Greetings Earthlings

It's not very nice coding, but it works.
I think there is a better way to do this, only I don't know it.
Perhaps someone else?

Greetz Daan

[muTual]

Yes it works! That's the point! That's what I was looking for!

I'm php coder for some time but I didn't know about eval() function in php. I'm so embarrassed. To punish myself I have to read PHP Documentation once again (and rewrite it!) :wink:

I'm interested too if there is some other solution.

Sorry for disturbance. I'm very grateful for help.

[Jay]

For the way you want to do it, the best solution is the eval() one!