String of file_get_html can't be edited? - php

Question

Consider this simple piece of code, working normally using the PHP Simple HTML DOM Parser, it outputs current community.
<?php
//PHP Simple HTML DOM Parser from simplehtmldom.sourceforge.net
include_once('simple_html_dom.php');
//Target URL
$url = 'http://stackoverflow.com/questions/ask';
//Getting content of $url
$doo = file_get_html($url);
//Passing the variable $doo to $abd
$abd = $doo ;
//Trying to find the word "current community"
echo $abd->find('a', 0)->innertext; //Output: current community.
?>
Consider this other piece of code, same as above but I add an empty space to the parsed html content (in the future, I need to edit this string, so I just added a space here to simplify things).
<?php
//PHP Simple HTML DOM Parser from simplehtmldom.sourceforge.net
include_once('simple_html_dom.php');
//Target URL
$url = 'http://stackoverflow.com/questions/ask';
//Getting content of $url
$doo = file_get_html($url);
//Passing the variable $url to $doo - and adding an empty space.
$abd = $doo . " ";
//Trying to find the word "current community"
echo $abd->find('a', 0)->innertext; //Outputs: nothing.
?>
The second code gives this error:
PHP Fatal error: Call to undefined function file_get_html() in /home/name/public_html/code.php on line 5
Why can't I edit the string gotten from file_get_html? I need to edit it for many important reasons (like removing some scripts before processing the html content of the page). I also do not understand why is it giving the error that file_get_html() could not be found (It's clear we're importing the correct parser from the first code).
Additional note:
I have tried all those variations:
include_once('simple_html_dom.php');
require_once('simple_html_dom.php');
include('simple_html_dom.php');
require('simple_html_dom.php');

Answer 1

file_get_html() returns an object, not a string. Attempting to concatenate a string to an object will call the object's _toString() method if it exists, and the operation returns a string. Strings do not have a find() method.
If you want to do as you have described read the file contents and concatenate the extra string first:
$content = file_get_contents('someFile.html');
$content .= "someString";
$domObject = str_get_html($content);
Alternatively, read the file with file_get_html() and manipulate it with the DOM API.

Answer 2

$doo is not a string! It's an object, an instance of Simple HTML DOM. You can't call -> methods on strings, only on objects. You cannot treat this object like a string. Trying to concatenate something to it makes no sense. $abd in your code is the result of an object concatenated with a string; this either results in a string or an error, depending in the details of the object. What it certainly does not do is result in a usable object, so you certainly can't do $abd->find().
If you want to modify the content of the page, do it using the DOM API which the object gives you.