>FUNCTION Str2num
>LPARAMETERS tcStr,tnLen
>local lnRetVal
>lnRetVal = 0
>FOR ix=1 TO tnLen
> lnRetVal = lnRetVal + ASC(SUBSTR(tcStr,ix))*(256^(ix-1))
>endfor
>RETURN TRANSFORM(lnRetVal,'999,999,999,999,999')Cetin

This function can also be re-written as:

FUNCTION Str2num
LPARAMETERS tcStr, tnLen
LOCAL lnI, lnReturn
    lnReturn = 0
    FOR lnI = tnLen TO 1 STEP -1
        lnReturn = (lnReturn * 256) + ASC(SUBSTR(tcStr, lnI))
    NEXT
    RETURN TRANSFORM(lnReturn, '999,999,999,999,999')

It's a little less expensive (3.31 seconds compared to 4.13 seconds on 1M iterations), though it hardly matters.