Data update

Task/Extensible-prime-generator/C-sharp/extensible-prime-generator.cs

@@ -0,0 +1,88 @@
+using System.Collections;
+
+IEnumerable<int> StartSieve(int length)
+{
+    yield return 2;
+    BitArray sieve = new(length);
+    var i = 3;
+
+    while (i < length)
+    {
+        if (!sieve[i])
+        {
+            yield return i;
+            var j = i * i;
+
+            while (j < length)
+            {
+                sieve[j] = true;
+                j += i;
+            }
+        }
+
+        i += 2;
+    }
+}
+
+IEnumerable<int> AllPrimes()
+{
+
+    foreach (var prime in StartSieve(1000))
+    {
+        yield return prime;
+    }
+
+    var start = 1000;
+
+    while (true)
+    {
+        foreach (var prime in Sieve(start, 1000))
+        {
+            yield return prime;
+        }
+
+        start += 1000;
+    }
+}
+
+IEnumerable<int> Sieve(int start, int length)
+{
+    var sieve = new BitArray(length);
+
+    foreach (var p in AllPrimes().Skip(1).TakeWhile(n => n * n < start + length))
+    {
+        var j = p * ((start + p - 1) / p);
+
+        while (j < start + length)
+        {
+            sieve[j - start] = true;
+            j += p;
+        }
+    }
+
+    for (var j = 1 - (start % 2); j < length; j += 2)
+    {
+        if (!sieve[j])
+            yield return start + j;
+    }
+}
+
+Console.Write("First 20 primes:");
+
+foreach (var p in AllPrimes().Take(20))
+    Console.Write($" {p}");
+
+Console.WriteLine();
+Console.Write("Primes between 100 and 150:");
+
+foreach (var p in Sieve(100, 50))
+    Console.Write($" {p}");
+
+Console.WriteLine();
+Console.Write("Number of primes between 7700 and 8000:");
+var n = Sieve(7700, 300).Count();
+Console.WriteLine($" {n}");
+
+Console.Write("10000th prime:");
+var t = AllPrimes().Skip(9999).First();
+Console.WriteLine($" {t}");