Question

So, I’m a little bit confused by what I’m looking at. I’m converting a MongoDate to JSON using PHP’s json_encode function and built-in MongoDB stuff. The result is this within my JSON string that’s returned:

"date":{"sec":1344724737,"usec":0}}

I understand the sec value is UNIX epoch time (seconds from 00:00:00 UTC on 1 January 1970 to be more precise). However, I don’t know what the usec value is. Is it an unsigned integer value for the milliseconds? Should I be using sec to get the value? For the record, I’m converting this into an NSDate in an iOS application. It works that way, but I just like to know more about what these values are to make sure I am using the right one (and so I can sleep at night once it goes into production).

Answer 1

It’s an integer corresponding to the number of microseconds (μsec). You divide by 1000000 and add it to the sec value to get the full timestamp.