In VFP9

NVL(myfield, CAST(0 AS int))
* or
CAST(NVL(myfield, 0) AS int)

In VFP8 and earlier it isn't possible but you can create numeric field with enough size by specifying according number of zeros.

NVL(myfield, 0000000)

>How do you get NVL() to return an integer if value is null?
>