Check if two time objects are on the same Date in Go

Question

What is the best way to compare two time.Time objects to see if they are on the same calendar day?

I looked at using t.Truncate() but it can only truncate to hours. I know I can use t.GetDate() which is straightforward but still requires more lines of code than I think should be necessary.

Yes, but only if you are using a timezone with no daylight savings time. Days are not always 24 hours. — Colin Gislason
– Colin Gislason, Commented Jan 10, 2014 at 20:48
Are both times in the same timezone? If not, you need to be careful about what "on the same calendar day" means. — Paul Hankin
– Paul Hankin, Commented Jan 12, 2014 at 9:32
In this case they are the same timezone, but that is a good point. — Colin Gislason
– Colin Gislason, Commented Jan 13, 2014 at 19:38

peterSO · Accepted Answer · 2014-01-11 23:06:30Z

38

It's inefficient to parse the time for the date components three times by making separate method calls for the year, month, and day. Use a single method call for all three date components. From my benchmarks, it's nearly three times faster. For example,

import "time" func DateEqual(date1, date2 time.Time) bool { y1, m1, d1 := date1.Date() y2, m2, d2 := date2.Date() return y1 == y2 && m1 == m2 && d1 == d2 }

answered Jan 11, 2014 at 23:06

peterSO

168k32 gold badges302 silver badges293 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Tack D. Over a year ago

I know this is a very old post, but would this not also compare the actual time, like hours and seconds instead of just they day, month and year?

Mough Over a year ago

it would not actually, check this out: pkg.go.dev/time#Time.Date, the Date() function will only return the year, month and day from the timestamp

Twyx Over a year ago

Note: This does not account for times with different timezones. For example one time at 6pm ET will not equal a UTC timestamp for 7pm ET (which would be midnight UTC). You have to make sure you first convert both times to the same timezone first.

thwd · Accepted Answer · 2014-01-10 20:26:12Z

12

if a.Day() == b.Day() && a.Month() == b.Month() && a.Year() == b.Year() { // same date }

answered Jan 10, 2014 at 20:26

thwd

25k8 gold badges79 silver badges110 bronze badges

Comments

Liam Galvin · Accepted Answer · 2018-03-14 10:31:33Z

3

You can truncate to days too, by using:

t.Truncate(time.Hour * 24)

answered Mar 14, 2018 at 10:31

Liam Galvin

7263 silver badges12 bronze badges

1 Comment

Leandri Over a year ago

Apparently only works on UCT time, because it states in the Truncate() doc, that the calculation is performed "since the zero time", and in the Time type docs that "The zero value of type Time is January 1, year 1, 00:00:00.000000000 UTC." according to source

SinaMobasheri · Accepted Answer · 2023-07-09 21:15:48Z

Another way around this is to get the string representation of dates from both times and compare them:

func sameDay(date, another time.Time) bool { return date.Format(time.DateOnly) == another.Format(time.DateOnly) }

Collectives™ on Stack Overflow

Check if two time objects are on the same Date in Go

4 Answers 4

3 Comments

Comments

1 Comment

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

3 Comments

Comments

1 Comment

Comments

Linked

Related