First you need to learn the syntax of C.
What you have shows us that you don't really understand some pretty basic concepts in C.
For example:
if(month=1,3,5,7,8,10,12){
will assign the value 1 to month and will
always take the branch.
This is
not how to check for one of a set of values.
You seem to think that
=
is the equality comparison operator and that
<=
is assignment. Neither is correct!