C # calculate the number of days between two dates

In SQL, select datediff ("DD", joindatetime, getdate () from DB

So what about C #?

// Use timespan in C # To calculate the difference between the two time points
// You can add any time unit between two dates.
Private string datediff (datetime datetime1, datetime datetime2)
{String datediff = NULL;
Timespan ts1 = new timespan (datetime1.ticks );
Timespan ts2 = new timespan (datetime2.ticks );
Timespan Ts = ts1.subtract (ts2). duration ();
Datediff = ts. days. tostring () + "day" + ts. hours. tostring () + "Hour" + ts. minutes. tostring () + "Minute" + ts. seconds. tostring () + "seconds ";
Return datediff;
}

Timespan Ts = date1-date2;
Double ddays = ts. totaldays; // Number of days with decimals. For example, if one day is 12 hours, 1.5 is returned.
Int ndays = ts. Days; // Integer Number of days. The result is 1 for 12 hours per day or 20 hours per day.

/// <Summary>
/// Calculate the interval between two dates
/// </Summary>
/// <Param name = "datetime1"> first date and time </param>
/// <Param name = "datetime2"> Second Date and time </param>
/// <Returns> </returns>
Private string datediff (datetime datetime1, datetime datetime2)
{
String datediff = NULL;

Timespan ts1 = new timespan (datetime1.ticks );
Timespan ts2 = new timespan (datetime2.ticks );
Timespan Ts = ts1.subtract (ts2). duration ();
Datediff = ts. Days. tostring () + "day"
+ Ts. Hours. tostring () + "hour"
+ Ts. Minutes. tostring () + "Minute"
+ Ts. Seconds. tostring () + "seconds ";

Return datediff;
}

Note:
1. The datetime Value Type represents a specific date time between 00:00:00 on January 1, January 1, 0001 AD and on January 1, December 31, 9999 AD. Therefore, you can use the datetime value type to describe any time within the expected range. A datetime value represents a specific time.
2. the timespan value contains many attributes and methods for accessing or processing a timespan value.
The following list covers some of them:
Add: adds the value to another timespan value.
Days: returns the timespan value calculated by the number of days.
Duration: gets the absolute value of timespan.
Hours: returns the hourly timespan value.
Milliseconds: returns the timespan value in milliseconds.
Minutes: returns the timespan value calculated in minutes.
Negate: returns the opposite number of the current instance.
Seconds: returns the timespan value calculated in seconds.
Subtract: Subtract another timespan value from it.
Ticks: the number of tick values returned for timespan.
Totaldays: returns the number of days indicated by the timespan value.
Totalhours: returns the number of hours represented by the timespan value.
Totalmilliseconds: the number of milliseconds in which the timespan value is returned.
Totalminutes: returns the number of minutes represented by the timespan value.
Totalseconds: returns the number of seconds represented by the timespan value.

///

// Date comparison
///
/// current date
// input date
// compare days
// returns true if the number of days is greater, false
private bool comparedate (string today, string writedate, int N)
{< br> datetime today = convert. todatetime (today);
datetime writedate = convert. todatetime (writedate);
writedate = writedate. adddays (n);
If (today> = writedate)
return false;
else
return true;