Something wrong with this if statement?

I can't get this line to work, it looks like it should work, but...

if( (square1=1 && square2=1 && square3=1) || (square4=1 && square5=1 && square6=1) || (square7=1 && square8=1 && square9=1) )

I get the error: Lvalue required in function Checkforwin()

According to some tutorials, Lvalue means a variable, and the square# 's are already variables.

Some help, please?

Yes, I know, just another Tic Tac Toe program.

the equality operator in C is '==' not '=', which is reserved for assignment

A'ight 'en
Worked like a charm, thanks.

Cheers.