In a String why "+" and not "&&"

1

As i was playing around , “trying” to help out dave in the other thread “Email form, button with If statement” I came across a conclusion ( with the help from Digitalosophy (see code below))

but what confused me is that i used “+” in a string to check all 3 conditions . Originally i thought that “&&” would of been used instead of “+” to check all 3 conditions but it didnt seem to work. Is there a reason why ? or when one or the other should be used.


on (press) {
        if (!sender_title.length + !sender_artist.length + !party_location.length) {
                stop();
        } else {
                play();
        }
}

What i have read up was that “+” is called a addition or string concatenation (or to link together)

Can anyone clear this up for me.

thanks.

::Soulty:::smirk::