function isInteger(para)
       on error resume next
       dim str
       dim l,i
       if isNUll(para) then
          isInteger=false
          exit function
       End if
       str=cstr(para)
       if trim(str)="" then
          isInteger=false
          exit function
       End if
       l=len(str)
       for i=1 to l
           if mid(str,i,1)>"9" or mid(str,i,1)<"0" then
              isInteger=false
              exit function
           End if
       next
       isInteger=true
       if err.number<>0 then err.clear
End function