PHP newbie has newbie question

[goodgeneguo]

Hi I just get started with PHP so this question is probably quite dumb. (but i could not find answers to it by searching google or PHP.net)
I saw some code like :  $variable1 .= $variable2;  What does this mean?  What is the difference from $variable1 = $variable2 ?
thank you for your attention

[roopurt18]

It's string concatenation.

$var = 'Hello';
$var .= ', World!';
echo $var;

Outputs:
Hello, World!

[Psycho]

That is the same thing as:

$variable1 = $variable1 . $variable 2;

So if $variable1 = "Tom" and $variable2 = "Jones" and you run

$variable1 .= $varialbe2

Then $variable1 will now equal "TomJones"

[roopurt18]

I guess I should have been more specific.  I may be mistaken, but I believe all operators of the form:
$var1 [i]op[/i]= $var2;

are equivalent to:
$var1 = $var1 [i]op[/i] $var2;

I.E:
$var1 = $var1 + $var2 is equivalent to $var1 += $var2
$var1 = $var1 . $var2 is equivalent to $var1 .= $var2

[Orio]

You are right.

Orio.