go Common standard library -time

Basic use

time.Time Type represents time . We can go through time.Now() Function to get the current time object , Then obtain the date, month, hour, minute, second and other information of the time object .

func main() {
    
	t := time.Now()
	fmt.Println(t)		// 2022-07-19 09:50:29.8980644 +0800 CST m=+0.003829601
	year := t.Year()     // year  
	month := t.Month()   // month 
	day := t.Day()       // Japan 
	hour := t.Hour()     // Hours 
	minute := t.Minute() // minute 
	second := t.Second() // second 
	fmt.Printf("%d-%02d-%02d %02d:%02d:%02d\n", year, month, day, hour, minute, second)  // 2022-07-19 09:50:29
}

func main() {
    
	time.Sleep(3*time.Second)  //  A dead sleep 3 second 
}

Time stamp

The time stamp is from 1970 year 1 month 1 Japan （08:00:00GMT） Computer and a Nian , The total number of milliseconds to the current time . It's also called Unix Time stamp （UnixTimestamp）.

func main() {
    
    t := time.Now()
    timestamp1 := t.Unix()     // Time stamp  
	timestamp2 := t.UnixNano() // Nanosecond time stamp  
	fmt.Printf("current timestamp1:%v\n", timestamp1)  // current timestamp1:1658195429
	fmt.Printf("current timestamp2:%v\n", timestamp2)  // current timestamp2:1658195429898064400
}

Timestamp objects can also be accessed through time.Unix() Convert to formatted time object , And through .Format() Method specifies the format and outputs

func main() {
    
	timestamp := time.Now().Unix()   
	tm := time.Unix(timestamp,0)   // timestamp  It can be released  int64  A number of bit type as a timestamp  
	fmt.Printf(tm.Format("2006-01-02 03:04:05 PM"))    // 2022-07-19 09:57:03 AM
	fmt.Printf(tm.Format("02/01/2006 15:04:05 PM"))    // 19/07/2022 09:57:03 AM
}

The time interval

time.Duration yes time A type of package definition , It represents the time between two time points , In nanoseconds .time.Duration A time interval , The longest period that can be expressed is about 290 year .

time The constants of the interval type defined in the package are as follows ：

const (
    Nanosecond  Duration = 1
    Microsecond          = 1000 * Nanosecond
    Millisecond          = 1000 * Microsecond
    Second               = 1000 * Millisecond
    Minute               = 60 * Second
    Hour                 = 60 * Minute
)
//time.Duration Express 1 nanosecond ,time.Second Express 1 second .

Time operation

Add

Time adds up

func (t Time) Add(d Duration) Time

for instance , seek 24 Hours later ：

func main() {
    
	var now time.Time = time.Now()
	lastTime:=now.Add(24*time.Hour)
	fmt.Println(lastTime)
}

Sub

Find the difference between two times

func (t Time) Sub(u Time) Duration

If the result exceeds Duration The maximum value that can be expressed / minimum value , Will return the maximum / minimum value .

To get a point in time Time-Duration, have access to t.Add(-Duration)

Calculate the difference between two time objects , If you calculate the difference between time and time interval , Use Add

func main() {
    
	var start time.Time = time.Now()
	var end=time.Now()
	fmt.Println(end.Sub(start))
}

Equal

func (t Time) Equal(u Time) bool

Determine if the two times are the same , Will consider the impact of time zone , Therefore, the standard time of different time zones can also be correctly compared .

This method and use ==( Double equal sign ) Different , This method also compares location and time zone information .

Before

func (t Time) Before(u Time) bool

If t The representative's time is u Before , Return to true ; Otherwise return false .

After

func (t Time) After(u Time) bool

If t The representative's time is u after , Return to true ; Otherwise return false .

func main() {
    
	var start time.Time = time.Now()
	var end=time.Now()
	fmt.Println(end.Before(start))
	fmt.Println(end.After(start))
}

Time format

There's a way for time types Format format , It should be noted that Go Formatting time templates in languages is not common Y-m-d H:M:S But use Go The birth time of 2006 year 1 month 2 Number 15 spot 04 branch （ The formula of memory is 2006 1 2 3 4）

- 2006 It refers to the year （Y）
- 01 It refers to the month （m）
- 02 On behalf of the sun （d）
- 15 When referring to （H）
- 04 Refers to points （M）
- 05 Refers to seconds （S）

// If you want to format it as 12 Hour mode , Need to specify PM
// If you want to keep the specified number of decimal places, write 0, If you want to omit the last possible 0 Just write  9
func main() {
    
	var now time.Time = time.Now()
	fmt.Println(now.Format("2006-01-02"))
	fmt.Println(now.Format("2006 year 01 month 02 Japan "))
	fmt.Println(now.Format("2006-01-02 15:02:05"))
	fmt.Println(now.Format("2006-01-02 03:04:05 PM"))
	//  Write... After the decimal point 0, Because there is 4 individual 0 Therefore, the result of formatted output is also retained 4 Decimal place 
	fmt.Println(now.Format("2006-01-02 15:04:05.0000")) //2022-03-19 00:50:09.7412
	//  Write... After the decimal point 9, If the end is 0, Will be omitted 
	fmt.Println(now.Format("2006-01-02 15:04:05.9999")) 
	//  Format only the hours, minutes and seconds 
	fmt.Println(now.Format("15:04:05"))
	//  Format only the date part 
	fmt.Println(now.Format("2006.01.02"))

}

Format the string into time

func main() {
    
	timeObj,err:=time.Parse("2006-01-02 15:04:05.9999","2022-03-19 00:10:42.96")
	if err != nil {
    
		fmt.Println(" Conversion error ",err)
	}
	//  Default to utc Time 
	fmt.Println(timeObj)
	fmt.Println(timeObj.Year())
	fmt.Println(timeObj.Month())
	fmt.Println(timeObj.Day())
	fmt.Println(timeObj.Hour())
	fmt.Println(timeObj.Minute())
	fmt.Println(timeObj.Second())
	now:=time.Now()

	res:=now.Sub(timeObj)
	fmt.Println(res) //  The current time minus the converted time , Poor discovery 8 Hours 

	//time.ParseInLocation The function needs to specify additional time zone information when parsing .
	//  Parse string time in the specified time zone and format 
	loc, err := time.LoadLocation("Asia/Shanghai")
	timeObj2, err := time.ParseInLocation("2006-01-02 15:04:05", "2022-03-19 00:10:42", loc)
	if err != nil {
    
		fmt.Println(err)
		return
	}
	fmt.Println(timeObj2)
	res=now.Sub(timeObj2)
	fmt.Println(res) //  This time is normal 
}

The time zone

The world is divided into 24 Time zone . China is almost across the world 5 Time zone , However, for convenience, only the standard time of Dongba time zone, i.e. Beijing time, shall prevail

func main() {
    
	shanghaiTime, err := time.LoadLocation("Asia/Shanghai") //  Only Chongqing Asia/chongqin, Shanghai Asia/Shanghai.. Some cities 
	//tokyo, err := time.LoadLocation("Asia/Tokyo")
	if err != nil {
    
		fmt.Println(" Error loading ", err)
		return
	}
	fmt.Println(shanghaiTime)


	//  To create a time object, you need to specify a location . Common locations are  time.Local（ Local time ）  and  time.UTC（UTC Time ）.
	//timeInLocal := time.Date(2009, 1, 1, 20, 0, 0, 0, time.Local) //  System local time 
	timeInUTC := time.Date(2022, 3, 15, 12, 3, 4, 0, time.UTC)
	sameTimeInBeijing := time.Date(2022, 3, 15, 20, 3, 4, 0, shanghaiTime)

	//  Beijing time. （ East eight ） Than UTC Good morning! 8 Hours , So the above two times seem to be different 8 Hours , But it means the same time 
	timesAreEqual := timeInUTC.Equal(sameTimeInBeijing)
	fmt.Println(timesAreEqual)

}

Timing task

Please refer to go timer One article