PHP Concatenation assignment

Question

Basic question using .= (concatenation assignment) in a loop.

This code produces this PHP error:

Notice: Undefined variable: html

for($i=0; $i<4; $i++) {
    $html .= "<h1>Stuff</h1>";
}

If I add an $html = ""; before the loop the error is corrected. Is this the best way to correct this, or am I missing something?

How do I use the .= operator within a loop, and any direction to tutorials to better understand this would be appreciated?

you need to add the $html = "" outside of the loop else you are attempting to concatenate null with a string which wont work. Thus your correction of adding $html = "" before the loop is correct. — Matt
– Matt, Commented Jun 21, 2016 at 19:45
@Matt Technically, it will work. It generates a notice, but PHP will treat the undefined variable as "" and do the concatenation anyway. — Don't Panic
– Don't Panic, Commented Jun 21, 2016 at 19:55
Does the answer fixes notice you were receiving? If yes could you accept answer, else please provide more details / questions. — Perdeep Singh
– Perdeep Singh, Commented Jun 23, 2016 at 0:37

Perdeep Singh · Accepted Answer · 2016-06-21 19:48:59Z

1

$html .= "something";

Above code is translated to:

$html = $html."something";

so you are trying to concatenate "something" to $html and since $html is not initialised thus you getting the error.

So please initialise the $html above loop and that's the correct way.

answered Jun 21, 2016 at 19:48

Perdeep Singh

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