>>
>>You will get 4 with an Integer type field because an integer is store as a 4-byte binary value. If you want the number of digits stored in a integer type field you might try Len(AllTrim(Str(fieldname))). This will get the number of digits.
>>
>>Hope this helps.
>
>Yes this works. But now I remember why I did not use this: I loose the decimals in this case. Some fields have decimals (normally two), others not. How can I determine whether a field has decimals? When I know this, I can use STR(fieldname,NrOfDecimals) and the problem is solved.

Use AFIELDS() to populate an array. It'll contain the total width of the field and the number of decimal places, if applicable.