yyyy-MM-dd HH:mm:ss time format time stamp comprehensive interpretation super detailed

Time format

time format (protocol)	describe
gg	The period or era.
y	The year without the era. Does not have leading zeros.
yy	The year without the era. with leading zeros.
yyyy	Four-digit year containing the era.
M	month number. Single-digit months have no leading zeros.
MM	month number. Single-digit months have a leading zero.
MMM	The abbreviated name of the month, as defined in AbbreviatedMonthNames.
MMMM	The full name of the month, as defined in MonthNames.
d	the day of the month. Single-digit dates have no leading zeros.
dd	the day of the month. Single-digit dates have a leading zero.
ddd	The abbreviated name of the day of the week, as defined in AbbreviatedDayNames.
dddd	The full name of the day of the week, as defined in DayNames.
h	Hours on a 12-hour clock. Single-digit hours have no leading zeros.
hh	Hours on a 12-hour clock. Single-digit hours have leading zeros.
H	The hour in 24-hour format. Single-digit hours have no leading zeros.
HH	The hour in 24-hour format. Single-digit hours have leading zeros.
m	minute. Single-digit minutes without leading zeros.
mm	minute. Single-digit minutes have a leading zero.
s	Second. Single-digit seconds without leading zeros.
ss	Second. Single-digit seconds have a leading zero.
f	Seconds have a decimal precision of one digit. The remaining digits are truncated.

String to time format conversion

Python

String to time format:

import datetime

str_time = '2022-01-01 12:00:00'
time_obj = datetime.datetime.strptime(str_time, '%Y-%m-%d %H:%M:%S')

Convert time format to string:

time_obj = datetime.datetime.now()
str_time = time_obj.strftime('%Y-%m-%d %H:%M:%S')

Java

String to time format:

import java.text.SimpleDateFormat;
import java.util.Date;

String str_time = "2022-01-01 12:00:00";
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date time_obj = formatter.parse(str_time);

Convert time format to string:

Date time_obj = new Date();
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String str_time = formatter.format(time_obj);

C++

String to time format:

#include <iostream>
#include <ctime>
#include <string>

std::string str_time = "2022-01-01 12:00:00";
struct tm time_obj;
strptime(str_time.c_str(), "%Y-%m-%d %H:%M:%S", &time_obj);
time_t timestamp = mktime(&time_obj);

Convert time format to string:

time_t timestamp = time(NULL);
struct tm time_obj = *localtime(&timestamp);
char str_time[20];
strftime(str_time, sizeof(str_time), "%Y-%m-%d %H:%M:%S", &time_obj);
std::string result(str_time);

Kotlin

String to time format:

fun main() {
    
        
val timeString = "2023-03-02T12:34:56"    
val pattern = "yyyy-MM-dd'T'HH:mm:ss"    
val formatter = java.time.format.DateTimeFormatter.ofPattern(pattern)    
val dateTime = java.time.LocalDateTime.parse(timeString, formatter)    
println(dateTime)
}

Convert time format to string:

import java.time.LocalDate
import java.time.format.DateTimeFormatter

fun main(args: Array<String>) {
    
    
    // Format y-M-d or yyyy-MM-d
    val string = "2017-07-25"
    val date = LocalDate.parse(string, DateTimeFormatter.ISO_DATE)

    println(date)
}

Shell

date to string

date +%F  #输出格式 YYYY-MM-DD
date +'%F %H:%m:%S' #输出格式 YYYY-MM-DD HH:mm:ss

string to date

date -d '2016-12-27'
date -d '2016-12-27' +%s #转成时间戳

C

TIME ToTimeStamp(string strTime)
{
    
    
tm _tm;
int year, month, day, hour, minute,second;
sscanf(strTime.c_str(), "%d-%d-%d %d:%d:%d", &year, &month, &day, &hour, &minute, &second);
_tm.tm_year = year - 1900;
_tm.tm_mon = month - 1;
_tm.tm_mday = day;
_tm.tm_hour = hour;
_tm.tm_min = minute;
_tm.tm_sec = second;
_tm.tm_isdst = 0;
time_t t = mktime(&_tm);
return t;
}

C#

date to string

DateTimeFormatInfo dfInfo=new DateTimeFormatInfo();
dfInfo.ShortDatePattern = "yyyy/MM/dd hh:mm:ss:ffff";
DateTime dt = Convert.ToDateTime("2019/07/01 18:18:18:1818", dfInfo);
string dateString = dt.ToString();
//或者
dateString = dt.ToString("yyyy-MM-dd HH:mm:ss");

string to date

string str=yyyy-MM-dd hh:mm:ss;
Convert.ToDateTime(str);
//例如
string dateString = "20190701 18:18:18:1818";
DateTime dt = DateTime.ParseExact(dateString, "yyyyMMddHHmmssffff", CultureInfo.CurrentCulture);
DateTime.ParseExact(dateString, "yyyyMMddHHmmssffff", CultureInfo.InvariantCulture);

javascript

date to string

function dateToString (date){
    
     
   var  year = date.getFullYear(); var  month =(date.getMonth() + 1).toString(); var  day = (date.getDate()).toString();  
   if  (month.length == 1) {
    
     
       month =  "0"  + month; 
   } 
   if  (day.length == 1) {
    
     
       day =  "0"  + day; 
   }
   var  dateTime = year +  "-"  + month +  "-"  + day;
   return  dateTime; 
}

string to date

function stringToDate (dateStr,separator){
    
    
      if (!separator){
    
    
             separator= "-" ;
      }
      var  dateArr = dateStr.split(separator);var  year = parseInt(dateArr[0]);var  month;                      
      if (dateArr[1].indexOf( "0" ) == 0){
    
    
          month = parseInt(dateArr[1].substring(1));
      } else {
    
    
           month = parseInt(dateArr[1]);
      }
      var  day = parseInt(dateArr[2]);
      var  date =  new  Date(year,month -1,day);
      return  date;
  }

Or directly annotate the parameters

@DateTimeFormat(pattern = "yyyy-MM-dd")
@JsonFormat(timezone = "GMT+8", pattern = "yyyy-MM-dd")

timestamp

A timestamp is a number in seconds representing the time since January 1, 1970 (UTC time).
To convert timestamps to other time formats, you can use built-in functions or libraries in various programming languages.

For example, in Python, you can use the datetime function in the datetime module to convert a timestamp to a time string.

from datetime 
import datetimetimestamp = 1609459200
# 转换为本地时间
dt_obj = datetime.fromtimestamp(timestamp)
# 转换为指定的格式
time_str = dt_obj.strftime('%Y-%m-%d %H:%M:%S')print(time_str)  
# Output: "2021-01-01 00:00:00"

Note that the timestamp is based on UTC time. If you need to convert it to local time, you need to use the fromtimestamp function instead of the utcfromtimestamp function.