How do I get the AM/PM value from a DateTime?

The code in question is below:

public static string ChangePersianDate(DateTime dateTime)
{
    System.Globalization.GregorianCalendar PC = new System.Globalization.GregorianCalendar();
    PC.CalendarType = System.Globalization.GregorianCalendarTypes.USEnglish;
    return
    PC.GetYear(dateTime).ToString()
    + "/"
    + PC.GetMonth(dateTime).ToString()
    + "/"
    + PC.GetDayOfMonth(dateTime).ToString()
    + ""
    + PC.GetHour(dateTime).ToString()
    + ":"
    + PC.GetMinute(dateTime).ToString()
    + ":"
    + PC.GetSecond(dateTime).ToString()
    + " "
    ????????????????
}

how can I get the AM/PM from the dateTime value?

How about:

dateTime.ToString("tt", CultureInfo.InvariantCulture);

string.Format("{0:hh:mm:ss tt}", DateTime.Now)

This should give you the string value of the time. tt should append the am/pm.

You can also look at the related topic:

How do you get the current time of day?

The DateTime should always be internally in the "american" (Gregorian) calendar. So if you do

var str = dateTime.ToString(@"yyyy/MM/dd hh:mm:ss tt", new CultureInfo("en-US"));

you should get what you want in many less lines.