if statement with a list problem

[psycorpse]

Can someone tell me if this is possible and give a little advice. I have a variable called $serviceIds. This variable contains a list like this: '1','2','3' ... Not those numbers exect but you get the point. I was trying to do an if statement that said
if($this_variable in ($serviceIds)){
do something;
}

Is this possible? If it is what may i be doing wrong. The error message that I get is:

Parse error: parse error, unexpected T_STRING in

[Weedpacket]

[man]in_array[/man]?

[psycorpse]

Thanks,

I wasn't sure how that was used and I didn't even think of the this morning.......