为什么我不能在PHP中回显此多维数组的值？

Question

This is so incredibly basic that I am totally baffled as to why it doesn't work. I have an array called $elements , and I want to just echo out one of the values.

I use NetBeans as an IDE, and if I use that to examine the contents of the multidimensional array in question, it looks like this:

So far as I can tell, everything looks normal. It is a multidimensional array, where the first level is numbered "0", and the second level has four named entries.

I just want to echo the value of "parameters", which is a string.

However, this code outputs nothing:

echo "This is the value of 'parameters': " .  $elements[0]['parameters'];

Have I got this most basic code wrong in some way?

---

This is what I get if I do var_dump($elements) :

array(1) { [0]=> object(Element)#3 (4) { ["type":"Element":private]=> string(4) "Text" ["resource":"Element":private]=> string(1) "0" ["parameters":"Element":private]=> string(209) "IP1 111.111.111.111 IP2 222.222.222.222 IP3 333.333.333.333 IP4 444.444.444.444 IP5 555.555.555.555 IP6 666.666.666.666 IP7 777.777.777.777 IP8 888.888.888.888 IP9 999.999.999.999 IP10 111.111.111.112" ["parent":"Element":private]=> NULL } }

... and this is the output from print_r($elements) :

Array ( [0] => Element Object ( [type:Element:private] => Text [resource:Element:private] => 0 [parameters:Element:private] => IP1 111.111.111.111 IP2 222.222.222.222 IP3 333.333.333.333 IP4 444.444.444.444 IP5 555.555.555.555 IP6 666.666.666.666 IP7 777.777.777.777 IP8 888.888.888.888 IP9 999.999.999.999 IP10 111.111.111.112 [parent:Element:private] => ) ) 

Answer 1

Your var dump is saying that element 0 is an object, so you will need to access it like so:

echo $elements[0]->parameters;

The problem is that from your dump, the parameters element is marked as private, so you will not be able to access it.

Solutions are:

• Change parameters to public
• Write a getter ( getParameters() ) and use that method to get your parameters.

Answer 2

Entry 0 at $elements is not just an array of attributes it's a class Element instance so in order to access its properties do something like:

echo( $elements[ 0 ]->parameters );

Although the parameters field seems private so you'd better add an accessor method to the object like getParameters() which would be public and return the value of parameters.