Question

c#随机数Random怎么每次都是一样的呀。

private void button1_Click(object sender, EventArgs e)
{
Random rd = new Random();
string str="server=(local);database=ConsultationDB;uid=sa;pwd=111";
string sqlselect = "select * from client_ProductInfo where CompanyID=" + textBox1.Text;
SqlConnection conn=new SqlConnection(str);
SqlCommand comm = new SqlCommand(sqlselect,conn);
SqlDataAdapter sda = new SqlDataAdapter(comm);
//sda.SelectCommand.CommandText = sqlselect;
DataSet ds = new DataSet();
conn.Open();
comm.ExecuteNonQuery();
sda.Fill(ds);
for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
{
String sqlinsert = "update client_ProductInfo set Hits=" + rd.Next(1000,5000) + " where CompanyID=" + textBox1.Text;
comm.CommandText = sqlinsert;
comm.ExecuteNonQuery();
}
MessageBox.Show("ok");
}

哪里错了呢

Answer 1

for(int i=0;i<100;i++)
{
Random ra = new Random((unchecked((int)DateTime.Now.Ticks + i)));
int num = ra.Next(1, 100); //1到100范围内的整数
}

DateTime.Now.Ticks 和 i是种子了，当然，你可以换成其他整数的

因为如果是时间作种子，显然，批量生成的时候，会有问题，所以我就加了个i

Answer 2

Random rd = new Random();
不要放在CLICk事件里面 或者更改种子

Answer 3

Random r = new Random(DateTime.Now.Ticks);