Command for today's date in two specific formats (12 Dec 17 and 12 December 2017)

Question

I want to be able to just type either the short version or long version by a command, like \longtoday and \shorttoday. Some more examples of short dates are 12 May 17 and 01 Jan 07, long dates are the same, except written out months and years, 12 May 2017 and 01 January 2007.

I was thinking of using isodate, but I can't figure out how it works quite that well. Can anyone help? Thank you!

Answer 1

You can do it with datetime2.

\documentclass{article}
\usepackage{datetime2}

\DTMusemodule{english}{en-GB}
\DTMnewdatestyle{long}{%
  \renewcommand{\DTMdisplaydate}[4]{%
    \number##3~\DTMenglishmonthname{##2}~\number##1\relax
  }%
  \renewcommand{\DTMDisplaydate}{\DTMdisplaydate}%
}
\DTMnewdatestyle{short}{%
  \renewcommand{\DTMdisplaydate}[4]{%
    \number##3~\DTMenglishshortmonthname{##2}~\number##1\relax
  }%
  \renewcommand{\DTMDisplaydate}{\DTMdisplaydate}%
}
\newcommand{\longtoday}{{\DTMsetdatestyle{long}\today}}
\newcommand{\shorttoday}{{\DTMsetdatestyle{short}\today}}

\begin{document}

\longtoday

\shorttoday

\end{document}

Answer 2

The following should do.

\documentclass[]{article}

\newcommand\defdate[3]{% Just for testing purpose
  \day=#1\relax
  \month=#2\relax
  \year=#3\relax
  \ignorespaces}

\def\JayLaoneShortyear#1#2#3\relax{%
  #3}
\def\JayLaoneDayTWODIGITS#1#2\relax{%
  \if\relax\detokenize{#2}\relax
    0#1%
  \else
    #1#2%
  \fi}

\newcommand*{\shorttoday}{%
  \expandafter\JayLaoneDayTWODIGITS\number\day\relax\space
  \ifcase\month
    \or Jan%
    \or Feb%
    \or Mar%
    \or Apr%
    \or May%
    \or Jun%
    \or Jul%
    \or Aug%
    \or Sep%
    \or Oct%
    \or Nov%
    \or Dec\fi
  \space
  \expandafter\JayLaoneShortyear\number\year\relax
}
\newcommand*{\longtoday}{%
  \expandafter\JayLaoneDayTWODIGITS\number\day\relax\space
  \ifcase\month
    \or January%
    \or February%
    \or March%
    \or April%
    \or May%
    \or June%
    \or July%
    \or August%
    \or September%
    \or October%
    \or November%
    \or December\fi
    \space
    \number\year
}

\begin{document}
\noindent
\defdate{1}{12}{2018}
\shorttoday\\
\longtoday\\
\defdate{7}{1}{2010}
\shorttoday\\
\longtoday\\
\defdate{17}{1}{2009}
\shorttoday\\
\longtoday
\end{document}

Answer 3

Another (but shorter) method with datetime2:

\documentclass{article}
\usepackage[en-GB]{datetime2}

\newcommand{\longtoday}{{\DTMlangsetup[en-GB]{abbr=false,ord=omit}\today}}
\newcommand{\shorttoday}{{\DTMlangsetup[en-GB]{abbr,ord=omit}\today}}

\begin{document}

\longtoday

\shorttoday

\end{document}

If the date needs to appear in the PDF bookmarks, then you need to set the style before the sectioning command. For example:

\documentclass{article}
\usepackage[en-GB]{datetime2}
\usepackage{hyperref}

% default setting:
\DTMlangsetup[en-GB]{abbr=false,ord=omit}

\begin{document}
\DTMlangsetup[en-GB]{abbr}
\section{\today}

\DTMlangsetup[en-GB]{abbr=false}
\section{\today}

\end{document}

Similarly for any other expandable context, such as writing the date to an external file.

If you want to ensure two-digit day of month (without an ordinal suffix):

\renewcommand*{\DTMenglishordinal}[1]{\DTMtwodigits{#1}}