golang's time package: methods for time interval formatting and output of timestamp formats such as seconds, milliseconds, and nanoseconds

获取当前时间的年、月、日、时、分、The method of seconds is as follows：

	// 获取当前时间
	now := time.Now()

	// 当前时间的年、月、日、小时、分钟、Both seconds and nanoseconds can be obtained directly through the existing interface
	year := now.Year()
	month := now.Month()
	day := now.Day()
	hour := now.Hour()
	minute := now.Minute()
	second := now.Second()
	nanosecond := now.Nanosecond()

	// The microseconds and milliseconds of the current time are generated by nanosecond calculations
	microsecond := nanosecond / 1e3
	millisecond := nanosecond / 1e6

	fmt.Println(now.Format("2006-01-02 15:04:05.000000000"))
	fmt.Println(year, month, day, hour, minute, second, nanosecond, microsecond, millisecond)

运行结果如下：

# 当前时间格式输出
2022-06-09 19:25:52.022598620
2022 June 9 19 25 52 22598620 22598 22

获取从1970The method of the elapsed time up to now is as follows：

	// 获取从1970经过的时间,Both seconds and nanoseconds can be obtained directly through the existing interface
	sec := now.Unix()     // Timestamp bits are 10
	ms := now.UnixMilli() // Timestamp bits are 13
	us := now.UnixMicro() // Timestamp bits are 16
	ns := now.UnixNano()  // Timestamp bits are 19
	fmt.Printf("sec:%v
 ms:%v
 us:%v
 ns:%v
", sec, ms, us, ns)

运行结果如下：

# 1970Elapsed time format output
sec:1654773952
 ms:1654773952022
 us:1654773952022598
 ns:1654773952022598620

Time interval formatted output method：

	// The time interval returns yestime.Duration,下面以1h1m1s1ms1us1nsexample of time intervals,Test the printing effect of various formats
	duration := 1*time.Hour + 1*time.Minute + 1*time.Second +
		1*time.Millisecond + 1*time.Microsecond + 1*time.Nanosecond
	// 直接使用%v打印,不转换sec、ms或其他.
	fmt.Printf("duration:%v
", duration)
	fmt.Printf("duration:%6v
", duration)
	fmt.Printf("duration:%.6v
", duration)
	fmt.Printf("duration:%.3v
", duration)

	// duration支持Hours()、 Minutes()、Seconds() 和
	// Milliseconds()、Microseconds()、Nanoseconds()接口
	// The first three interface return types are float64可以通过0.3fPrint the number after the decimal point,
	// 后三个为int64,是整数,小数点后都是0
	// The following lists the format printing of seconds and milliseconds,Other time units can refer to seconds and milliseconds

	// Print format for seconds%fAfter the decimal point can be printed9位,精确到纳秒
	fmt.Printf("duration:%vsec
", duration.Seconds())
	fmt.Printf("duration:%0.3fsec
", duration.Seconds())
	fmt.Printf("duration:%0.6fsec
", duration.Seconds())

	// Milliseconds have no decimal point,都是整数,转换成float后,小数点后都是0
	fmt.Printf("duration:%vms
", duration.Milliseconds())
	fmt.Printf("duration:%.3dms
", duration.Milliseconds())
	fmt.Printf("duration:%.3fms
", float64(duration.Milliseconds()))
}

行结果如下：

# 1h1m1s1ms1us1nsThe time interval example format output
# %vTime output without unit conversion
duration:1h1m1.001001001s
duration:1h1m1.001001001s
duration:1h1m1.
duration:1h1

# 秒的格式输出
duration:3661.001001001sec
duration:3661.001sec
duration:3661.001001sec

# Millisecond format output
duration:3661001ms
duration:3661001ms
duration:3661001.000ms

It can be seen through the test program：
1.Format output without time unit conversion,直接用%v能精确到ns,%.3V,Just cut the output string.Direct use is recommended here%v即可.
2.For second format output,%v精确到小数点9位,即纳秒.当然可以根据%fformat adjustment,例如%.3f精确到毫秒
3.For millisecond format output,直接用%v或%d即可,转换成float64没有意义

It is generally used to count how long a function or a program has been running,一般建议使用第二种方式,Convert output in seconds format,Then adjust according to the accuracy%f的格式即可.
In the first way, the time unit may not be uniform,For example one is minutes,一个是秒.

The completed code for the above example is as follows：

package main

import (
	"fmt"
	"time"
)

func main() {
	// 获取当前时间
	now := time.Now()

	// 当前时间的年、月、日、小时、分钟、Both seconds and nanoseconds can be obtained directly through the existing interface
	year := now.Year()
	month := now.Month()
	day := now.Day()
	hour := now.Hour()
	minute := now.Minute()
	second := now.Second()
	nanosecond := now.Nanosecond()

	// The microseconds and milliseconds of the current time are generated by nanosecond calculations
	microsecond := nanosecond / 1e3
	millisecond := nanosecond / 1e6

	fmt.Println(now.Format("2006-01-02 15:04:05.000000000"))
	fmt.Println(year, month, day, hour, minute, second, nanosecond, microsecond, millisecond)

	// 获取从1970经过的时间,Both seconds and nanoseconds can be obtained directly through the existing interface
	sec := now.Unix()     // Timestamp bits are 10
	ms := now.UnixMilli() // Timestamp bits are 13
	us := now.UnixMicro() // Timestamp bits are 16
	ns := now.UnixNano()  // Timestamp bits are 19
	fmt.Printf("sec:%v
 ms:%v
 us:%v
 ns:%v
", sec, ms, us, ns)


	// The time interval returns yestime.Duration,下面以1h1m1s1ms1us1nsexample of time intervals,Test the printing effect of various formats
	duration := 1*time.Hour + 1*time.Minute + 1*time.Second +
		1*time.Millisecond + 1*time.Microsecond + 1*time.Nanosecond
	// 直接使用%v打印,不转换sec、ms或其他.
	fmt.Printf("duration:%v
", duration)
	fmt.Printf("duration:%6v
", duration)
	fmt.Printf("duration:%.6v
", duration)
	fmt.Printf("duration:%.3v
", duration)

	// duration支持Hours()、 Minutes()、Seconds() 和
	// Milliseconds()、Microseconds()、Nanoseconds()接口
	// The first three interface return types are float64可以通过0.3fPrint the number after the decimal point,
	// 后三个为int64,是整数,小数点后都是0
	// The following lists the format printing of seconds and milliseconds,Other time units can refer to seconds and milliseconds

	// Print format for seconds%fAfter the decimal point can be printed9位,精确到纳秒
	fmt.Printf("duration:%vsec
", duration.Seconds())
	fmt.Printf("duration:%0.3fsec
", duration.Seconds())
	fmt.Printf("duration:%0.6fsec
", duration.Seconds())

	// Milliseconds have no decimal point,都是整数,转换成float后,小数点后都是0
	fmt.Printf("duration:%vms
", duration.Milliseconds())
	fmt.Printf("duration:%.3dms
", duration.Milliseconds())
	fmt.Printf("duration:%.3fms
", float64(duration.Milliseconds()))
}

Below is the source code for time unit conversion for time intervals：

// time.go

// Nanoseconds returns the duration as an integer nanosecond count.
func (d Duration) Nanoseconds() int64 { return int64(d) }

// Microseconds returns the duration as an integer microsecond count.
func (d Duration) Microseconds() int64 { return int64(d) / 1e3 }

// Milliseconds returns the duration as an integer millisecond count.
func (d Duration) Milliseconds() int64 { return int64(d) / 1e6 }

// These methods return float64 because the dominant
// use case is for printing a floating point number like 1.5s, and
// a truncation to integer would make them not useful in those cases.
// Splitting the integer and fraction ourselves guarantees that
// converting the returned float64 to an integer rounds the same
// way that a pure integer conversion would have, even in cases
// where, say, float64(d.Nanoseconds())/1e9 would have rounded
// differently.

// Seconds returns the duration as a floating point number of seconds.
func (d Duration) Seconds() float64 {
	sec := d / Second
	nsec := d % Second
	return float64(sec) + float64(nsec)/1e9
}

// Minutes returns the duration as a floating point number of minutes.
func (d Duration) Minutes() float64 {
	min := d / Minute
	nsec := d % Minute
	return float64(min) + float64(nsec)/(60*1e9)
}

// Hours returns the duration as a floating point number of hours.
func (d Duration) Hours() float64 {
	hour := d / Hour
	nsec := d % Hour
	return float64(hour) + float64(nsec)/(60*60*1e9)
}

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