Strange behavior in time.Parse function in Go

Question

When you execute the following code snippet, which is derived mainly from Go's time package documentation and its Parse function example:

package main

import (
   "time"
   "fmt"
)

var shortForm = "2006-Jan-02"
t, _ := time.Parse(shortForm, "2013-Feb-03")
fmt.Println(t)

Then, you can get the correct result, 2013-02-03 00:00:00 +0000 UTC, in your console.

However, when you change the shortForm value slightly, such as 2007-Jan-02, 2006-Feb-02, or 2006-Jan-01, it outputs wrong results, and the output looks not even regularly, such as 0001-01-01 00:00:00 +0000 UTC, 2013-03-01 00:00:00 +0000 UTC, or 2013-01-03 00:00:00 +0000 UTC.

So why does the function behave such strangely? And how can I deal with it? Every time I use the function, should I always define layout variable as 2006-Jan-02?

Thanks.

Answer 1

The time.Parse and time.Format functions use the numbers in the layout argument to identify which date component is referred to:

• 1: month (alternatively can appear in words as Jan / January)
• 2: day
• 3: hour (alternatively as 15 for 24 hour clock)
• 4: minute
• 5: second
• 6: year (alternatively as 2006 for 4 digit year)
• 7: time zone (alternatively as MST for time zone code).

So when you change the layout string from 2006-Jan-02 to 2006-Jan-01, you are saying that the month is represented in the time string twice, leading to unexpected results.