Random minutes in C# 2.0

问题

Ho do I go about adding random minutes to column in dataset, here is my code:

protected void btnUpdateTable_Click(object sender, EventArgs e)
{ 


    foreach (DataRow dr in ds.Tables[0].Rows)
    {
       ///check if column[logout] is null or empty, fill it
       if(dr.IsNull("logout_time"))
       {
           ///get the login colum datetime
           /// add random datetime to it
           if (!dr.IsNull("login_time"))
           {
               DateTime dt = Convert.ToDateTime(dr["login_time"]);
               dt = dt.AddMinutes(?);/// "?"<--here I want to add random minutes
           }            
       }
    }

Any help greatly appreciated.

Thank you all for the help, here my final Code snippet:

foreach (DataRow dr in ds.Tables[0].Rows)
    {
       ///check if column[logout] is null or empty, fill it
       if(dr.IsNull("logout_time"))
       {
           ///get the login colum datetime
           /// add random datetime to it
           if (!dr.IsNull("login_time"))
           {
               DateTime dt = Convert.ToDateTime(dr["login_time"]);
               Random rand = new Random();
               //return random.Next(0, 59);
               dt = dt.AddMinutes(rand.Next(0,59));
               dt = dt.AddSeconds(rand.Next(0, 59));
               dr["logout_time"] = dt;

           }

       }
    }

回答1:

You can use this:

Random random = new Random();

foreach(DataRow dr ...)
{
   int rand = random.Next(0, 60); 
}

As a comment pointed out, you don't need to create a new Random object for every number you wish to create. (Actually, you probably shouldn't).

回答2:

Try using Random:

Random randGen = new Random();

foreach (DataRow dr in ds.Tables[0].Rows)
{
   ///check if column[logout] is null or empty, fill it
   if(dr.IsNull("logout_time"))
   {
       ///get the login colum datetime
       /// add random datetime to it
       if (!dr.IsNull("login_time"))
       {
           DateTime dt = Convert.ToDateTime(dr["login_time"]);
           dt = dt.AddMinutes(randGen.Next(0, 60));
           /// "?"<--here I want to add random minutes
       }            
   }
}

回答3:

Assuming you don't want your dt object to get moved into the next hour (e.g., you would want any time between 8:00 and 8:59 to get moved up to 8:59 at most), I would suggest making the following changes:

protected void btnUpdateTable_Click(object sender, EventArgs e)
{ 
    Random rand = new Random;

    foreach (DataRow dr in ds.Tables[0].Rows)
    {
       ///check if column[logout] is null or empty, fill it
       if(dr.IsNull("logout_time"))
       {
           ///get the login colum datetime
           /// add random datetime to it
           if (!dr.IsNull("login_time"))
           {
               DateTime dt = Convert.ToDateTime(dr["login_time"]);
               dt = dt.AddMinutes(rand.Next(0, (60 - dt.Minutes)));
           }            
       }
    }
}

回答4:

Also please note that two if-statements within each other can be optimized to:

protected void btnUpdateTable_Click(object sender, EventArgs e) { 
    foreach (DataRow dr in ds.Tables[0].Rows)
       if(dr.IsNull("logout_time") && !dr.IsNull("login_time")) {
          DateTime loginTime = Convert.ToDateTime(dr["login_time"]);
          loginTime = loginTime.AddMinutes(new Random().Next(0,59));
       }
}

来源：https://stackoverflow.com/questions/1167440/random-minutes-in-c-sharp-2-0