NetBSD/gnu/usr.bin/bc/Examples/primes.b

33 lines
642 B
Brainfuck

/* An example that finds all primes between 2 and limit. */
define primes (limit) {
auto prime[], num, p, root, i
prime[1] = 2;
prime[2] = 3;
num = 2;
if (limit >= 2) print "prime 1 = 2\n"
if (limit >= 3) print "prime 2 = 3\n";
scale = 0;
for ( p=5; p <= limit; p += 2) {
root = sqrt(p);
isprime = 1;
for ( i = 1; i < num && prime[i] <= root; i++ ) {
if ( p % prime[i] == 0 ) {
isprime = 0;
break;
}
}
if (isprime) {
num += 1;
prime [num] = p;
print "prime ", num, " = ", p, "\n"
}
}
}
print "\ntyping 'primes (10)' will print all primes less than 10.\n"