Get last day in month of time.Time

Question

When I have a time.Time:

// January, 29th
t, _ := time.Parse("2006-01-02", "2016-01-29")

How can I get a time.Time which represents January 31st? This example is trivial, but when there's a date in February, the last day might be 28th or 29th.

Answer 1

Package time

func Date

func Date(year int, month Month, day, hour, min, sec, nsec int, loc *Location) Time

Date returns the Time corresponding to

yyyy-mm-dd hh:mm:ss + nsec nanoseconds

in the appropriate zone for that time in the given location.

The month, day, hour, min, sec, and nsec values may be outside their usual ranges and will be normalized during the conversion. For example, October 32 converts to November 1.

For example, normalizing a date,

package main

import (
    "fmt"
    "time"
)

func main() {
    // January, 29th
    t, _ := time.Parse("2006-01-02", "2016-01-29")
    fmt.Println(t.Date())
    // January, 31st
    y,m,_ := t.Date()
    lastday:= time.Date(y,m+1,0,0,0,0,0,time.UTC)
    fmt.Println(lastday.Date())
}

Output:

2016 January 29
2016 January 31