Primefinder.bas

const INITIAL_PRIMES = 2000 ' ~4kb initial buffer size
const MAX_NUMBER = 1000
dim as integer iTotalPrimes = 1 ' number of primes found
redim as integer iPrimes(INITIAL_PRIMES) ' list of primes

dim as double iStartTime, iEndTime
iPrimes(0) = 2 ' first prime is 2

iStartTime = timer
dim as integer iNum = 1 ' Starts counting at 3 (1+2)
while iNum < MAX_NUMBER
    iNum += 2
    for n as integer = 0 to iTotalPrimes-1
        if (iNum MOD iPrimes(n)) = 0 then continue while ' not prime

        if iPrimes(n) >= sqr(iNum) then
            'print "prime!", iNum
            iPrimes(iTotalPrimes) = iNum
            iTotalPrimes += 1
            if iTotalPrimes > ubound(iPrimes) then
                redim preserve iPrimes(ubound(iPrimes) + INITIAL_PRIMES)
            end if
            continue while
        end if
    next n
wend
iEndTime = timer


print str(iTotalPrimes)+" primes found in "+str(iEndTime-iStartTime)+" seconds"
print "Press any key to list primes..."
sleep
open "primes.txt" for output as #1
for i as integer = 0 to iTotalPrimes-1
    print #1, iPrimes(i);
next i
close #1

sleep