Ruby的strftime有没有一种格式可以用于表示月份但不带前导零？
我找到了%e可以用于获取没有前导零的日期，但在处理月份时遇到了麻烦。
最终想要的日期格式为：9/1/2010
4个回答
152
某些版本的strftime允许在格式化输出前导零时使用负号前缀，例如：
strftime "%-d/%-m/%y"
然而这将取决于您系统上的strftime。因此，为了保持一致性，我会改为这样：
dt = Time.local(2010, 'Sep', 1)
printf "%d/%d/%d", dt.day, dt.month, dt.year
- draegtun
10
2@Rob：只要你的系统的
strftime 支持它，它就可以工作（例如，在 Mac OSX Snow Leopard 上运行的 1.8.7 上无法工作）。 - draegtun对我来说可行。在Ubuntu上使用1.9.2p180。 - B Seven
无法在MacOS 10.6.8上使用REE 1.8.7，但可以在MacOS 10.8.2上使用REE 1.8.7。 - JNN
@draegtun：你能告诉我如何检查我系统上的
strftime版本吗？我有两台运行10.6.8和10.8.2的Macbook，几乎具有相同的RoR环境（REE 1.8.7-2012.02，RVM 1.19.5，Rubygem 1.8.23和1.8.15对应），但是在10.6.8上strftime('%-m_%-d_%Y')不起作用。谢谢。 - JNN尝试使用
man strftime命令，并查找...%-* GNU libc扩展。执行数字输出时不要进行任何填充。（在此manpage的底部附近）。 - draegtun显示剩余5条评论
43
以下是我参考的格式列表，来自2.1.3文档。根据这个列表，你需要使用
%-m：Date (Year, Month, Day):
%Y - Year with century (can be negative, 4 digits at least)
-0001, 0000, 1995, 2009, 14292, etc.
%C - year / 100 (rounded down such as 20 in 2009)
%y - year % 100 (00..99)
%m - Month of the year, zero-padded (01..12)
%_m blank-padded ( 1..12)
%-m no-padded (1..12)
%B - The full month name (``January'')
%^B uppercased (``JANUARY'')
%b - The abbreviated month name (``Jan'')
%^b uppercased (``JAN'')
%h - Equivalent to %b
%d - Day of the month, zero-padded (01..31)
%-d no-padded (1..31)
%e - Day of the month, blank-padded ( 1..31)
%j - Day of the year (001..366)
Time (Hour, Minute, Second, Subsecond):
%H - Hour of the day, 24-hour clock, zero-padded (00..23)
%k - Hour of the day, 24-hour clock, blank-padded ( 0..23)
%I - Hour of the day, 12-hour clock, zero-padded (01..12)
%l - Hour of the day, 12-hour clock, blank-padded ( 1..12)
%P - Meridian indicator, lowercase (``am'' or ``pm'')
%p - Meridian indicator, uppercase (``AM'' or ``PM'')
%M - Minute of the hour (00..59)
%S - Second of the minute (00..60)
%L - Millisecond of the second (000..999)
The digits under millisecond are truncated to not produce 1000.
%N - Fractional seconds digits, default is 9 digits (nanosecond)
%3N millisecond (3 digits)
%6N microsecond (6 digits)
%9N nanosecond (9 digits)
%12N picosecond (12 digits)
%15N femtosecond (15 digits)
%18N attosecond (18 digits)
%21N zeptosecond (21 digits)
%24N yoctosecond (24 digits)
The digits under the specified length are truncated to avoid
carry up.
Time zone:
%z - Time zone as hour and minute offset from UTC (e.g. +0900)
%:z - hour and minute offset from UTC with a colon (e.g. +09:00)
%::z - hour, minute and second offset from UTC (e.g. +09:00:00)
%Z - Abbreviated time zone name or similar information.
Weekday:
%A - The full weekday name (``Sunday'')
%^A uppercased (``SUNDAY'')
%a - The abbreviated name (``Sun'')
%^a uppercased (``SUN'')
%u - Day of the week (Monday is 1, 1..7)
%w - Day of the week (Sunday is 0, 0..6)
ISO 8601 week-based year and week number:
The first week of YYYY starts with a Monday and includes YYYY-01-04.
The days in the year before the first week are in the last week of
the previous year.
%G - The week-based year
%g - The last 2 digits of the week-based year (00..99)
%V - Week number of the week-based year (01..53)
Week number:
The first week of YYYY that starts with a Sunday or Monday (according to %U
or %W). The days in the year before the first week are in week 0.
%U - Week number of the year. The week starts with Sunday. (00..53)
%W - Week number of the year. The week starts with Monday. (00..53)
Seconds since the Epoch:
%s - Number of seconds since 1970-01-01 00:00:00 UTC.
Literal string:
%n - Newline character (\n)
%t - Tab character (\t)
%% - Literal ``%'' character
Combination:
%c - date and time (%a %b %e %T %Y)
%D - Date (%m/%d/%y)
%F - The ISO 8601 date format (%Y-%m-%d)
%v - VMS date (%e-%^b-%4Y)
%x - Same as %D
%X - Same as %T
%r - 12-hour time (%I:%M:%S %p)
%R - 24-hour time (%H:%M)
%T - 24-hour time (%H:%M:%S)
在2014年10月24日更新为最新的2.1.3文档
- Rob Cameron
5
7我正在寻找如何获取没有前导零的月份，而不是日期。 - Shpigford
2为什么每个人都在投票反对这篇文章？我认为拥有这个strftime助手列表会很有用！ - Rob Cameron
6我猜人们投票反对它是因为它没有回答问题。单独看这个列表相当有用，但是这些选项中没有一个能够防止 OP 所请求的月份前导零"0"的出现。 - Benry
1尽管这个问题没有回答原始问题，但对于那些在谷歌上搜索类似但不完全相同的问题的人来说，它仍然是有用的。 - David Oneill
1％e提供了一个前导空格（即“ 1/01/2012”），这可能是不必要的，也不一定是OP想要的。 - brad
11
文档显示有许多不同的配置数字格式的选项。除了使用%-d格式外，您还可以使用以下标志代替“-”：
Flags:
- don't pad a numerical output.
_ use spaces for padding.
0 use zeros for padding.
^ upcase the result string.
# change case.
: use colons for %z.
- typeoneerror
7
我曾经遇到过类似的问题，解决方法是将strftime("%m")转换成整数。
例如：
strftime("%m")+0 give the current month as integer 'without leading zero'
简单，但不够优雅。
- cyberw0rm
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