Determining the Last Day in a Given Month Using Time.Time

When working with time-based data, it's often necessary to determine the last day in a given month. Whether the month has 28, 29 (in leap years), or 30 or 31 days can make this a challenging task.

Time Package Solution

The Go time package provides a convenient solution with its Date function. The syntax for Date is:

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

To get the last day in a month, we can normalize the date by setting the day to 0. This will automatically adjust for the actual number of days in the month.

For example, to get the last day of January 2016:

package main

import (
    "fmt"
    "time"
)

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

    // Get year and month components
    y, m, _ := t.Date()

    // Normalize date to get last day of month
    lastday := time.Date(y, m 1, 0, 0, 0, 0, 0, time.UTC)

    fmt.Println(lastday.Date())
}
````

Output:

2016 January 31