Go golang time Now UnixNano convert to milliseconds

Question

How can I get Unix time in Go in milliseconds   I have the following function   func makeTimestamp   int64       return time Now   UnixNano     1e6   1e3     I need less precision and only want milliseconds

User · Answer

At https   github com golang go issues 44196 randall77 suggested time Now   Sub time Unix 0 0   Milliseconds    which exploits the fact that Go s time Duration already have  Milliseconds method

User · Answer

As  Jono points out in  OneOfOne s answer  the correct answer should take into account the duration of a nanosecond  Eg   func makeTimestamp   int64       return time Now   UnixNano      int64 time Millisecond  int64 time Nanosecond       OneOfOne s answer works because time Nanosecond happens to be 1  and dividing by 1 has no effect  I don t know enough about go to know how likely this is to change in the future  but for the strictly correct answer I would use this function  not OneOfOne s answer  I doubt there is any performance disadvantage as the compiler should be able to optimize this perfectly well   See https   en wikipedia org wiki Dimensional analysis  Another way of looking at this is that both time Now   UnixNano   and time Millisecond use the same units  Nanoseconds   As long as that is true  OneOfOne s answer should work perfectly well

User · Answer

Just divide it    func makeTimestamp   int64       return time Now   UnixNano     int64 time Millisecond      Here is an example that you can compile and run to see the output  package main  import        time       fmt     func main         a    makeTimestamp        fmt Printf   d  n   a     func makeTimestamp   int64       return time Now   UnixNano     int64 time Millisecond

User · Answer

Simple-read but precise solution would be   func nowAsUnixMilliseconds        return time Now   Round time Millisecond  UnixNano     1e6     This function    Correctly rounds the value to the nearest millisecond  compare with integer division  it just discards decimal part of the resulting value   Does not dive into Go-specifics of time Duration coercion     since it uses a numerical constant that represents absolute millisecond nanosecond divider    P S  I ve run benchmarks with constant and composite dividers  they showed almost no difference  so feel free to use more readable or more language-strict solution

User · Answer

Keep it simple   func NowAsUnixMilli   int64       return time Now   UnixNano     1e6

User · Answer

I think it s better to round the time to milliseconds before the division   func makeTimestamp   int64       return time Now   Round time Millisecond  UnixNano      int64 time Millisecond  int64 time Nanosecond       Here is an example program   package main  import            fmt           time     func main             fmt Println unixMilli time Unix 0  123400000            fmt Println unixMilli time Unix 0  123500000            m    makeTimestampMilli           fmt Println m          fmt Println time Unix m 1e3   m 1e3  int64 time Millisecond  int64 time Nanosecond       func unixMilli t time Time  int64           return t Round time Millisecond  UnixNano      int64 time Millisecond    int64 time Nanosecond      func makeTimestampMilli   int64           return unixMilli time Now        The above program printed the result below on my machine   123 124 1472313624305 2016-08-28 01 00 24 305  0900 JST

[time] Go / golang time.Now().UnixNano() convert to milliseconds?

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