Question

var_dump(implode(',', array('11','22')));

And

var_dump(implode(array('11','22'), ','));

Which is right?

Answer 1

According to the documentation on implode():

implode() can, for historical reasons, accept its parameters in either order. For consistency with explode(), however, it may be less confusing to use the documented order of arguments.

The documented description is:

string implode ( string $glue , array $pieces  ) 

implode(',', array('11','22')) (the documented order) is identical to implode(array('11','22'), ',')). Both create the string 11,22.