[PHP] whats wrong with this?

I just cant seem to work out why this doesn't work. My PHP book doesn't explain "if" statements very well so i have no idea if i am breaking a rule. $system_day = date("j"); for($day = 1; $day < 32; $day++){ if($day = $system_day){ echo "match!"; } else{

[PHP] quick question

hey people, I have been seeing something in a few php scripts i've been playing with and i really dont know what it means or does. I'm only new to php so maybe someone could explain. i have been seeing "->"...e.g. while($file = $dir -> read()) what does the "->" mean and do. thanks heaps -- P