算法。。。

1. 求100以内的所有质数

        private void button3_Click(object sender, EventArgs e)
        {
            System.Text.StringBuilder sb = new StringBuilder();

            int m;
            int j;

            for (int i = 2; i < 100; i++)
            {
                m = (int)Math.Sqrt(i);
                for (j = 2; j <= m; j++)
                {
                    if (i % j == 0)
                        break;
                }
                if (j > m)
                {
                    sb.Append(i.ToString() + ",");
                }
            }

            MessageBox.Show(sb.ToString());
        }