Passing variable (time) from one form to another C#

Let's say I have two forms. The first one will contain the start button and the other one is the stop button. Is there a way wherein I can determine the elapsed time between pressing the start and stop button and show it in the 2nd form.

I tried doing this and arrive at these codes

Form 1: Start button

namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
    public DateTime startTime2;
    public DateTime endTime;
    public TimeSpan ts_timeElapsed;
    public string s_timeElapsed;


    public Form1()
    {
        InitializeComponent();
    }

    private void StartButton_Click(object sender, EventArgs e)
    {
        startTime2 = DateTime.Now;
        Form2 frm = new Form2();
        frm.Show();
        this.Hide();


    }

    private void Button2_Click(object sender, EventArgs e)
    {
        Instructions frm = new Instructions();
        frm.Show();
        this.Hide();

    }


}
}

Form 2: Stop button

namespace WindowsFormsApplication1
{
public partial class RoadSign1Meaning : Form
{
    public DateTime startTime1;
    public DateTime endTime;
    public TimeSpan ts_timeElapsed;
    public string s_timeElapsed;

    public RoadSign1Meaning()
    {
        InitializeComponent();
    }
    public string GetElapsedTimeString()
    {
        int days = ts_timeElapsed.Days;
        int hours = ts_timeElapsed.Hours;
        int mins = ts_timeElapsed.Minutes;
        int secs = ts_timeElapsed.Seconds;
        string x = "";
        if (days != 0)
        {
            x += days.ToString() + ":";
        }
        if (hours != 0)
        {
            x += hours.ToString() + ":";
        }
        if (mins != 0)
        {
            x += mins.ToString() + ":";
        }
        if (secs != 0)
        {
            x += secs.ToString();
        }

        return x;
    }

    private void StopButton_Click(object sender, EventArgs e)
    {
                   endTime = DateTime.Now;
        ts_timeElapsed = (endTime - startTime1);
        s_timeElapsed = GetElapsedTimeString();
        ElapsedLabel.Text = "Time Elapsed: " + s_timeElapsed;

        Form3 frm = new Form3();
        frm.Show();
    }
}
}

However, the problem is the time value from form 1 is not save therefore form 2 display a wrong elapsed time value. Any suggestions to make my code work? Thanks!

Pass start time to second form

private void StartButton_Click(object sender, EventArgs e)
{
    Form2 frm = new Form2(DateTime.Now);
    frm.Show();
    this.Hide();
}

And then use it

public partial class Form2 : Form
{
    private DateTime startTime;

    public Form2(DateTime startTime)
    {
        InitializeComponent();
        this.startTime = startTime;
    }

    private void StopButton_Click(object sender, EventArgs e)
    {
        endTime = DateTime.Now;
        ts_timeElapsed = (endTime - startTime);
        s_timeElapsed = GetElapsedTimeString();
        ElapsedLabel.Text = "Time Elapsed: " + s_timeElapsed;

        Form3 frm = new Form3();
        frm.Show();
    }     
}

Depending on if these forms exist within the same application, you could pass a reference to the first form into the second. And then (because the starttime1 DateTime object is public, you can access it from the second form.

It would be cleaner and more maintainable if stored the data in a place that is accessible from both forms. For example a static class. (You could also use a database or text file)

public static TempStore
{
    public DateTime StartTime { get; set; }
}

Set StartTime from From1 and read back the difference in Form2

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void StartButton_Click(object sender, EventArgs e)
    {
        TempStore.StartTime = DateTime.Now;

        // ...
    }
}

Form 2:

public partial class RoadSign1Meaning : Form
{
    public RoadSign1Meaning()
    {
        InitializeComponent();
    }

    private void StopButton_Click(object sender, EventArgs e)
    {
        TimeSpan span = DateTime.Now - TempStore.StartTime;             

        // ...
    }
}

This way, if you decide to pass more data to and from forms you can extend this static class.

There are several solutions but also depends on the complexity of what would you like to achieve. The simplest one with less modifications in your code would be to declare a constructor on your second form which accepts a parameter of type DateTime and pass in startTime2 from Form1 when creating the Form2 just like Form2 form2 = new Form2(startTime2). A more elegant way would be to define an interface with a method GetElapsedTime() and create a concrete in which takes care of the start/end time and you can pass the concrete instance to Form2 like before from Form1.

来源：https://stackoverflow.com/questions/18311215/passing-variable-time-from-one-form-to-another-c-sharp

标签

forms

elapsedtime