How to access an object property with a minus-sign?

Question

I got an object (in PHP) and I can't print the content. In debug-mode it's like this:

stdClass Object
(
    [pre-selection] => 1
)

But I can't print the 'pre-selection' because of the minus sign.

echo $object->pre-selection; //doens't work.

How can I print this out? Thanks.

Answer 1

You could try

$object->{'pre-selection'};

http://php.net/manual/en/language.types.string.php#language.types.string.parsing.complex

See also Example 2 of json_decode()

Example #2 Accessing invalid object properties

Accessing elements within an object that contain characters not permitted under PHP's naming convention (e.g. the hyphen) can be accomplished by encapsulating the element name within braces and the apostrophe.

<?php

$json = '{"foo-bar": 12345}';

$obj = json_decode($json);
print $obj->{'foo-bar'}; // 12345

?>

Update (thanks to salathe):

Curly braces may also be used, to clearly delimit the property name. They are most useful when accessing values within a property that contains an array, when the property name is made of mulitple parts, or when the property name contains characters that are not otherwise valid

Answer 2

There are multiple ways, the problem is that the PHP tokenizer will choke on the - sign in the code, howver you can write it so that the parser does not complains:

echo $object->{'pre-selection'};

or

$property = 'pre-selection'
echo $object->$property;

or

$array = (array) $object;   
echo $array['pre-selection'];

In these cases, the PHP parser does not run about a place in the raw code that it has a problem to parse with any longer.

---

Wondering where this is documented. For example in the SimpleXML documentation:

Accessing elements within an XML document that contain characters not permitted under PHP's naming convention (e.g. the hyphen) can be accomplished by encapsulating the element name within braces and the apostrophe.

Example #3 Getting <line>

<?php
include 'example.php';

$movies = new SimpleXMLElement($xmlstr);

echo $movies->movie->{'great-lines'}->line;
?>

The above example will output:

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