PHP problem with && and possibly a malfuntioning array?

I have been working on this page for over a year now and I’m pretty sick of it but it was all going so well when I started…

I noticed I didn’t wrap my statements in () those things when using && but then again they do all get checked == against the same number (just 1, it’s a bunch of switches in an array)

if( $a[1]=1 && $a[2]==1 && $a[3]==1 ) { }
simplified but pretty much the deal

I was supposed to have four images and ony one showed up, and it’s in the wrong place. I also created a second array but left the first couple of values undefined.

$b[6]=2
for example

This project is massively… well, massive. So it would just be cruel to throw anyone else into it. But if any of the things I’ve mentioned might cause problems I’d like to know.