String.Format custom date and time format string

Standard date and time format strings

Date and time format strings define the textual representation of DateTime values ​​produced by formatting operations. It also defines the representation of date and time values ​​required in parse operations to successfully convert strings to dates and times. A custom format string consists of one or more custom date and time format specifiers. Any non-standard date and time format strings are interpreted as custom date and time format strings.

format specifier	illustrate	The C# example is taken from Microsoft's official documentation
"d"	Short date pattern.	2009-06-15T13:45:30 -> 6/15/2009
“D”	Long date pattern.	2009-06-15T13:45:30 -> Monday, June 15, 2009
“f”	Full date/time pattern (short time)	2009-06-15T13:45:30 -> Monday, June 15, 2009 1:45 PM
“F”	Full date/time pattern (long time)	2009-06-15T13:45:30 -> Monday, June 15, 2009 1:45:30 PM
“g”	Regular date/time pattern (short time)	2009-06-15T13:45:30 -> 6/15/2009 1:45 PM
“G”	Regular date/time pattern (long time)	2009-06-15T13:45:30 -> 6/15/2009 1:45:30 PM
“s”	Sortable date/time pattern	2009-06-15T13:45:30-> 2009-06-15T13:45:30
“t”	short time mode	2009-06-15T13:45:30 -> 1:45 PM
“T”	long time mode	2009-06-15T13:45:30 -> 1:45:30 PM
“u”	Generic Sortable Date/Time Pattern	2009-06-15T13:45:30 -> 2009-06-15 13:45:30Z
“U”	Generic full date/time pattern	2009-06-15T13:45:30 -> Monday, June 15, 2009 8:45:30 PM
“y”	year month pattern	2009-06-15T13:45:30 -> June 2009

How standard format strings work

In formatting operations, standard format strings are just aliases for custom format strings. The advantage of using an alias to refer to a custom format string is that although the alias remains fixed, the custom format string itself can vary. This is important because string representations of date and time values ​​often vary by culture. For example, the "d" standard format string indicates that date and time values ​​should be displayed using the short date pattern. For a fixed culture, this pattern is "MM/dd/yyyy".

Custom date and time format strings

format specifier	illustrate	The C# example is taken from Microsoft's official documentation
"d"	day of the month (1 to 31)	2009-06-01T13:45:30 -> 1 2009-06-15T13:45:30 -> 15
“dd”	Day of the month (01 to 31)	2009-06-01T13:45:30 -> 01 2009-06-15T13:45:30 -> 15
“ddd”	Abbreviated name of the day of the week	2009-06-15T13:45:30 -> My
"dddd"	The full name of the day of the week	2009-06-15T13:45:30 -> Monday
“f”	Tenths of a second in a date and time value	2009-06-15T13:45:30.6170000 -> 6 2009-06-15T13:45:30.05 -> 0
“ff”	The hundredths of a second in a date and time value	2009-06-15T13:45:30.6170000 -> 61 2009-06-15T13:45:30.0050000 -> 00
“fff”	Milliseconds of date and time values	6/15/2009 13:45:30.617 -> 617 6/15/2009 13:45:30.0005 -> 000
“ffff”	Ten-thousandths of a second in date and time values	2009-06-15T13:45:30.6175000 -> 6175 2009-06-15T13:45:30.0000500 -> 0000
“fffff”	Hundred-thousandths of a second in a date and time value	2009-06-15T13:45:30.6175400 -> 61754 6/15/2009 13:45:30.000005 -> 00000
"ffffff"	Millionths of a second in a date and time value	2009-06-15T13:45:30.6175420 -> 617542 2009-06-15T13:45:30.0000005 -> 000000
“fffffff”	Millionths of a second in a date and time value	2009-06-15T13:45:30.6175425 -> 6175425 2009-06-15T13:45:30.0001150 -> 0001150
“F”	If nonzero, the tenths of a second of the date and time value	2009-06-15T13:45:30.6170000 -> 6 2009-06-15T13:45:30.0500000 -> (no output)
“FF”	If nonzero, the hundredths of a second in the date and time value.	2009-06-15T13:45:30.6170000 -> 61 2009-06-15T13:45:30.0050000 -> (no output)
“FFF”	If nonzero, the thousandths of a second for date and time values	2009-06-15T13:45:30.6170000 -> 617 2009-06-15T13:45:30.0005000 ->（无输出）
“FFFF”	如果非零，则为日期和时间值的万分之几秒	2009-06-15T13:45:30.5275000 -> 5275 2009-06-15T13:45:30.0000500 ->（无输出）
“FFFFF”	如果非零，则为日期和时间值的十万分之几秒	2009-06-15T13:45:30.6175400 -> 61754 2009-06-15T13:45:30.0000050 ->（无输出）
“FFFFFF”	如果非零，则为日期和时间值的百万分之几秒	2009-06-15T13:45:30.6175420 -> 617542 2009-06-15T13:45:30.0000005 ->（无输出）
“FFFFFFF”	如果非零，则为日期和时间值的千万分之几秒	2009-06-15T13:45:30.6175425 -> 6175425 2009-06-15T13:45:30.0001150 -> 000115
“g”、“gg”	时期或纪元	2009-06-15T13:45:30.6170000 -> A.D.
“h”	采用 12 小时制的小时（从 1 到 12）	2009-06-15T01:45:30 -> 1 2009-06-15T13:45:30 -> 1
“hh”	采用 12 小时制的小时（从 01 到 12）	2009-06-15T01:45:30 -> 01 2009-06-15T13:45:30 -> 01
“H”	采用 24 小时制的小时（从 0 到 23）	2009-06-15T01:45:30 -> 1 2009-06-15T13:45:30 -> 13
“HH”	采用 24 小时制的小时（从 00 到 23）。	2009-06-15T01:45:30 -> 01 2009-06-15T13:45:30 -> 13
“K”	时区信息	2009-06-15T13:45:30, Kind Unspecified -> 2009-06-15T13:45:30, Kind Utc -> Z 2009-06-15T13:45:30, Kind Local -> -07:00（取决于本地计算机的设置）
“m”	分钟（0 到 59）	2009-06-15T01:09:30 -> 9 2009-06-15T13:29:30 -> 29
“mm”	分钟（00 到 59）	2009-06-15T01:09:30 -> 09 2009-06-15T01:45:30 -> 45
“M”	月份（1 到 12）	2009-06-15T13:45:30 -> 6
“MM”	月份（1 到 12）	2009-06-15T13:45:30 -> 06
“MMM”	月份的缩写名称	2009-06-15T13:45:30 -> Jun
“MMMM”	月份的完整名称	2009-06-15T13:45:30 -> June
“s”	秒（0 到 59）	2009-06-15T13:45:09 -> 9
“ss”	秒（00 到 59）	2009-06-15T13:45:09 -> 09
“t”	AM/PM 指示符的第一个字符	2009-06-15T13:45:30 -> P
“tt”	AM/PM 指示符	2009-06-15T13:45:30 -> PM
“y”	年份（0 到 99）	0001-01-01T00:00:00 -> 1 0900-01-01T00:00:00 -> 0 1900-01-01T00:00:00 -> 0 2009-06-15T13:45:30 -> 9 2019-06-15T13:45:30 -> 19
“yy”	年份（00 到 99）	0001-01-01T00:00:00 -> 01 0900-01-01T00:00:00 -> 00 1900-01-01T00:00:00 -> 00 2019-06-15T13:45:30 -> 19
“yyy”	年份（最少三位数字）	0001-01-01T00:00:00 -> 001 0900-01-01T00:00:00 -> 900 1900-01-01T00:00:00 -> 1900 2009-06-15T13:45:30 -> 2009
“yyyy”	由四位数字表示的年份	0001-01-01T00:00:00 -> 0001 0900-01-01T00:00:00 -> 0900 1900-01-01T00:00:00 -> 1900 2009-06-15T13:45:30 -> 2009
“yyyyy”	由五位数字表示的年份	0001-01-01T00:00:00 -> 00001 2009-06-15T13:45:30 -> 02009
“z”	相对于 UTC 的小时偏移量，无前导零。	2009-06-15T13:45:30-07:00 -> -7
“zz”	相对于 UTC 的小时偏移量，带有表示一位数值的前导零。	2009-06-15T13:45:30-07:00 -> -07
“zzz”	相对于 UTC 的小时和分钟偏移量	2009-06-15T13:45:30-07:00 -> -07:00
":"	时间分隔符	2009-06-15T13:45:30 -> :
"/"	日期分隔符。	2009-06-15T13:45:30 -> /
"string" 'string'	文本字符串分隔符	2009-06-15T13:45:30 ("arr:" h:m t) -> arr: 1:45 P
%	将下面的字符定义为自定义格式说明符。	2009-06-15T13:45:30 (%h) -> 1
\	转义字符	2009-06-15T13:45:30 (h \h) -> 1 h
任何其他字符	字符将复制到未更改的结果字符串。	2009-06-15T01:45:30 (arr hh:mm t) -> arr 01:45 A

 示例：在Unity中测试

using System;
using UnityEngine;

public class StringText : MonoBehaviour
{

    void Start()
    {
        //21:37:09
        Debug.LogFormat("{0:HH:mm:ss}", DateTime.Now);
        //09:37:09 下午
        Debug.LogFormat("{0:hh:mm:ss tt}", DateTime.Now);
        //2022-06-10
        Debug.LogFormat("{0:yyyy-MM-dd}", DateTime.Now);
        //2022:06:10
        Debug.LogFormat("{0:yyyy:MM:dd}", DateTime.Now);
        //2022/06/10
        Debug.LogFormat("{0:yyyy/MM/dd}", DateTime.Now);
        //2022年06月10日
        Debug.LogFormat("{0:yyyy年MM月dd日}", DateTime.Now);
        //2022年06月10日 09:39:55 下午
        Debug.LogFormat("{0:yyyy年MM月dd日 hh:mm:ss tt}", DateTime.Now);
        //2022年06月10日 21:40:32
        Debug.LogFormat("{0:yyyy年MM月dd日 HH:mm:ss}", DateTime.Now);
        //A.D. 2022年06月10日 21:42:14
        Debug.LogFormat("{0:g yyyy年MM月dd日 HH:mm:ss}", DateTime.Now);
        //2022 - 06 - 10 21:43:21Z
        Debug.LogFormat("{0:u}", DateTime.Now);
        //2022年6月10日 13:47:04
        Debug.LogFormat("{0:U}", DateTime.Now);
        //21:47
        Debug.LogFormat("{0:t}", DateTime.Now);
        //21:47:04
        Debug.LogFormat("{0:T}", DateTime.Now);
        //2022-06-10T21:47:04
        Debug.LogFormat("{0:s}", DateTime.Now);
        //2022/6/10 21:47
        Debug.LogFormat("{0:g}", DateTime.Now);
        //2022/6/10 21:47:04
        Debug.LogFormat("{0:G}", DateTime.Now);
        //2022年6月10日 21:47:04
        Debug.LogFormat("{0:F}", DateTime.Now);
        //2022年6月10日 21:47
        Debug.LogFormat("{0:f}", DateTime.Now);
        //2022年6月10日
        Debug.LogFormat("{0:D}", DateTime.Now);
        //2022/6/10
        Debug.LogFormat("{0:d}", DateTime.Now);
        //六月
        Debug.LogFormat("{0:MMMM}", DateTime.Now);
        //21
        Debug.LogFormat("{0:HH}", DateTime.Now);
    }

}

运行效果：

 上述测试打印出来的Log

Log
21:58:00
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:10)

Log
09:58:00 下午
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:12)

Log
2022-06-10
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:14)

Log
2022:06:10
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:16)

Log
2022/06/10
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:18)

Log
2022年06月10日
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:20)

Log
2022年06月10日 09:58:00 下午
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:22)

Log
2022年06月10日 21:58:00
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:24)

Log
A.D. 2022年06月10日 21:58:00
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:26)

Log
2022-06-10 21:58:00Z
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:28)

Log
2022年6月10日 13:58:00
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:30)

Log
21:58
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:32)

Log
21:58:00
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:34)

Log
2022-06-10T21:58:00
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:36)

Log
2022/6/10 21:58
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:38)

Log
2022/6/10 21:58:00
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:40)

Log
2022年6月10日 21:58:00
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:42)

Log
2022年6月10日 21:58
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:44)

Log
2022年6月10日
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:46)

Log
2022/6/10
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:48)

Log
六月
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:50)

Log
21
UnityEngine.Debug:LogFormat (string,object[])
StringText:Start () (at Assets/StringText.cs:52)

一个应用示例演示：