foreach rule to count non-empty fields

How do you write a foreach loop that will iterate through every field in the data file, and count the number of non-empty fields?

something like this ...

var counter=0;

foreach (field in my data file) {
  if (field > "")
  then counter++
}

display counter;

var n=0;

for (var i in FusionPro.Fields)
   if (Field(i)) n++;

return n;