C#中通过ref传递的参数

Question

I'm new to programming and right now I'm doing some exercises, however, I couldn't complete one task (or I didn't understand), I'm stuck at number (3), can you help me ? Here's exercise and my code:

(1)Should have a separate method for conversion

(2)Should have a separate method called ConvertSecondsToHoursMinutesSeconds

(3)Should have one int parameter passed by value and three int parameters passed by ref

(4)Should correctly convert seconds to hours, minutes and seconds

  public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        conversion();
    }
    private void ConvertSecondsToHoursMinutesSecondsMethod(long totalSeconds) 
    {
        long hours, mins, secs, v;

        hours = totalSeconds / 3600;
        v = totalSeconds % 3600;
        mins = v / 60;
        secs = v % 60;
    }
    private void conversion(ref long hours, ref long secs, ref long mins)

    {
        long seconds = Convert.ToInt64(userInputLabel.Text);
        ConvertSecondsToHoursMinutesSecondsMethod(seconds);

        outputLabel.Content = $"{hours} {mins} {secs}";


    }
}

Answer 1

You need to pass the ref parameters received to the other method you are calling for them to receive correct values. Local variables usually fail to exist once a method returns.

private void ConvertSecondsToHoursMinutesSecondsMethod(long totalSeconds, ref long secs, ref long mins) 
{
    hours = totalSeconds / 3600;
    long v = totalSeconds % 3600;
    mins = v / 60;
    secs = v % 60;
}

private void conversion()
{
    long hours, secs, mins;
    long seconds = Convert.ToInt64(userInputLabel.Text);
    ConvertSecondsToHoursMinutesSecondsMethod(seconds, ref hours, ref secs, ref mins);

    outputLabel.Content = $"{hours} {mins} {secs}";
}

Answer 2

Try this

Also have a look at https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/ref for the correct way to use ref

public MainWindow()
{
    InitializeComponent();

}

private void Button_Click(object sender, RoutedEventArgs e)
{
    Conversion();
}
private void ConvertSecondsToHoursMinutesSecondsMethod(int totalSeconds, ref long hours, ref long secs, ref long min)
{
    long v;
    hours = totalSeconds / 3600;
    v = totalSeconds % 3600;
    min = v / 60;
    secs = v % 60;
}
private void Conversion()
{
    long hours = 0;
    long secs = 0;
    long mins = 0;
    int seconds = Convert.ToInt32(userInputLabel.Text);

    ConvertSecondsToHoursMinutesSecondsMethod(seconds, ref hours, ref mins, ref secs);

    outputLabel.Content = $"{hours} {mins} {secs}";
}