Saving DateTime as something else than string

So i have a code where i get the system time when you start and when you quit but they are both saved as strings, i want to subtract them to find the time the player has had the app quit. How would you store system time as a number you can subtract or how would you subtract them as strings?

 

You can use the DateTime object included with C#, it handles subtracting dates as you'd expect.

 

The "native" form of a DateTime is a long (long integer) which can be converted by reading dateTime.Ticks, or reconstituted into a DateTime using the constructor DateTime(yourLongNumber). How to save this number may vary; if you're using JSON or something similar it's easy as you can just put the field in there, but if using PlayerPrefs you'll have more difficulty because it doesn't have a SetLong method; in that case, you should find a tutorial and use a JSON based save method, it's just better.

As far as subtracting them, you can subtract two DateTimes directly, which will give you a TimeSpan object.