Does anyone know how to determine the number of variables in a Filemaker array?

FileMaker doesn't really have arrays. Maybe you can restate what you mean?

Well, in Filemaker one can assign a variable as follows:

$travelAmount[1]

$travelAmount[2]

$travelAmount[3]

$travelAmount[4]

From non-Filemaker experience, the above would be considered an array. I want to know if it is possible to count how many iterations there are of the above array in Filemaker.

FM does not have "true" arrays in the sense. So there is no function to figure out exactly how many variables with the same name have data in it.

For a good read, here is a recent discussion regarding FM vepeating variables.

Repeating Variables