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参数为空或为零的新命令

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参数为空或为零的新命令

我在其他主题中阅读了代码：定义了newcommand selectTask。

如果 TaskOne/TaskTwo = 空白则可以。

现在我想编辑 IF TaskOne/TaskTwo = 空白或零（0）。

请帮助更新此代码：

\newcommand{\selectTask}[2]{%
  \if\relax#1\relax
    \if\relax#2\relax
      \selectTaskA % 00 TaskOne = TaskTwo=blank => How if blank or zero?
    \else
      \selectTaskB % 01 TaskOne =blank,TaskTwo=!=blank
    \fi
  \else
    \if\relax#2\relax
      \selectTaskC % 10  TaskOne !=blank, TaskTwo=blank
    \else
      \selectTaskD % 11 TaskOne = TaskTwo!=blank
    \fi
  \fi
}

如果数据为零或空白，请帮忙。提前谢谢

答案1

\if\relax#1\relax 如果扩展的#1结果以任何非字符开头，则为真。\if\relax\hbox{abc}\relax例如，测试结果为真（和类型为abc）。

这使用\ifx不扩展测试标记的测试。

\def\tmpempty{}
\def\tmpzero{0}

\newcommand{\selectTask}[2]{%
  \def\tmp{#1}\ifx\tmp\tmpempty\let\tmp\tmpzero\fi
  \def\tmpb{#2}\ifx\tmpb\tmpempty\let\tmpb\tmpzero\fi
  \ifx\tmp\tmpzero
    \ifx\tmpb\tmpzero
      \show\selectTaskA % 00 TaskOne = TaskTwo=blank => How if blank or zero?
    \else
      \show\selectTaskB % 01 TaskOne =blank,TaskTwo=!=blank
    \fi
  \else
    \ifx\tmpb\tmpzero
      \show\selectTaskC % 10  TaskOne !=blank, TaskTwo=blank
    \else
      \show\selectTaskD % 11 TaskOne = TaskTwo!=blank
    \fi
  \fi
}



\selectTask{}{}%A
\selectTask{0}{}%A
\selectTask{}{x}%B
\selectTask{0}{x}%B
\selectTask{x}{}%C
\selectTask{x}{0}%C
\selectTask{x}{y}%D





\stop

答案2

以下是按照您的想法实现的：测试第一个参数是否为空，如果为空则使用参数调用以下宏0；同样测试第二个参数。然后我们进行字符串大小写选择。

\documentclass{article}
\usepackage{xparse}

\ExplSyntaxOn

\NewExpandableDocumentCommand{\selectTask}{mm}
 {
  \latexforti_select_task:nn { #1 } { #2 }
 }

\cs_new:Nn \latexforti_select_task:nn
 {
  \tl_if_blank:nTF { #1 }
   {
    \__latexforti_select_task_a:nn { 0 } { #2 }
   }
   {
    \__latexforti_select_task_a:nn { #1 } { #2 }
   }
 }
\cs_new:Nn \__latexforti_select_task_a:nn
 {
  \tl_if_blank:nTF { #2 }
   {
    \__latexforti_select_task_b:nn { #1 } { 0 }
   }
   {
    \__latexforti_select_task_b:nn { #1 } { #2 }
   }
 }
\cs_new:Nn \__latexforti_select_task_b:nn
 {
  \str_case:nn { #1#2 }
   {
    {00}{\selectTaskA}
    {01}{\selectTaskB}
    {10}{\selectTaskC}
    {11}{\selectTaskD}
   }
 }

\ExplSyntaxOff

\newcommand{\selectTaskA}{I'm task A}
\newcommand{\selectTaskB}{I'm task B}
\newcommand{\selectTaskC}{I'm task C}
\newcommand{\selectTaskD}{I'm task D}

\begin{document}

\selectTask{0}{0} --- \selectTask{}{0} -- \selectTask{0}{}

\selectTask{0}{1} --- \selectTask{}{1}

\selectTask{1}{0} --- \selectTask{1}{}

\selectTask{1}{1}

\end{document}

在此处输入图片描述

具有更多经典方法的实现（但参数不能{ }像前一个那样）。

\documentclass{article}

\makeatletter

\newcommand{\selectTask}[2]{%
  \expandafter\latexforti@select\expandafter
    {\number0#1\expandafter}\expandafter{\number0#2}%
}
\newcommand{\latexforti@select}[2]{%
  \ifcase\numexpr#1*2+#2\relax % the arguments are binary digits!
    \selectTaskA
  \or
    \selectTaskB
  \or
    \selectTaskC
  \or
    \selectTaskD
  \fi
}
\makeatother

\newcommand{\selectTaskA}{I'm task A}
\newcommand{\selectTaskB}{I'm task B}
\newcommand{\selectTaskC}{I'm task C}
\newcommand{\selectTaskD}{I'm task D}

\begin{document}

\selectTask{0}{0} --- \selectTask{}{0} -- \selectTask{0}{}

\selectTask{0}{1} --- \selectTask{}{1}

\selectTask{1}{0} --- \selectTask{1}{}

\selectTask{1}{1}

\end{document}

答案3

如果参数是仅有的允许为空白或数字，则可以使用\ifnum比较。

\documentclass[]{scrartcl}
\def\selectTaskA{00}
\def\selectTaskB{01}
\def\selectTaskC{10}
\def\selectTaskD{11}

\newcommand{\selectTask}[2]{%
  \ifnum9=#19\relax
    \ifnum9=#29\relax
      \selectTaskA
    \else
      \selectTaskB
    \fi
  \else
    \ifnum9=#29\relax
      \selectTaskC
    \else
      \selectTaskD
    \fi
  \fi
}
\begin{document}
\selectTask{}{}\\
\selectTask{0}{}\\
\selectTask{}{0}\\
\selectTask{0}{0}\\
\selectTask{}{1}\\
\selectTask{1}{}\\
\selectTask{1}{1}
\end{document}

答案4

这是一个基于扩展的变体，即，不进行任何临时赋值。除此之外，它不进行任何\if..-primitives（这可以避免参数本身包含不平衡的\if../ \else/时出现的问题\fi）。

\documentclass[a4paper]{article}
\usepackage{textcomp}
\makeatletter
%%----------------------------------------------------------------------
%% Check whether argument is empty:
%%......................................................................
%% \UD@CheckWhetherNull{<Argument which is to be checked>}%
%%                     {<Tokens to be delivered in case that argument
%%                       which is to be checked is empty>}%
%%                     {<Tokens to be delivered in case that argument
%%                       which is to be checked is not empty>}%
%% The gist of this macro comes from Robert R. Schneck's \ifempty-macro:
%% <https://groups.google.com/forum/#!original/comp.text.tex/kuOEIQIrElc/lUg37FmhA74J>
\newcommand\UD@CheckWhetherNull[1]{%
  \romannumeral0\expandafter\@secondoftwo\string{\expandafter
  \@secondoftwo\expandafter{\expandafter{\string#1}\expandafter
  \@secondoftwo\string}\expandafter\@firstoftwo\expandafter{\expandafter
  \@secondoftwo\string}\expandafter\expandafter\@firstoftwo{ }{}%
  \@secondoftwo}{\expandafter\expandafter\@firstoftwo{ }{}\@firstoftwo}%
}%
%%----------------------------------------------------------------------
%% Check whether argument is blank (empty or only space tokens):
%%......................................................................
%% -- Take advantage of the fact that TeX discards space tokens when
%%    "fetching" _un_delimited arguments: --
%% \UD@CheckWhetherBlank{<Argument which is to be checked>}%
%%                      {<Tokens to be delivered in case that
%%                        argument which is to be checked is blank>}%
%%                      {<Tokens to be delivered in case that argument
%%                        which is to be checked is not blank}%
\newcommand\UD@CheckWhetherBlank[1]{%
  \romannumeral\expandafter\expandafter\expandafter\@secondoftwo
  \expandafter\UD@CheckWhetherNull\expandafter{\@firstoftwo#1{}.}%
}%
%%----------------------------------------------------------------------
%% Check whether argument is blank (empty or only space tokens) or
%% consists only of a _single_ token "0" (charcode 48(dec), catcode 12(dec))
%%......................................................................
\newcommand\UD@GobbleToExclam{}\long\def\UD@GobbleToExclam#1!{}%
\newcommand\UD@forkzero{}\long\def\UD@forkzero#1!!0!#2#3!!!!{#2}%
\newcommand\UD@zerofork[3]{%
  \expandafter\UD@CheckWhetherNull\expandafter{\UD@GobbleToExclam#1!}{%
    \UD@forkzero!#1!0!{#3}%<-case #1 is empty/has no tokens
                !!#1!{#2}%<-case #1 = "0"
                !!0!{#3}%<-case #1 something else without exclamation mark
                !!!!%
  }{#3}%<-case #1 = something else with exclamation-mark.
}%
\newcommand\UD@CheckWhetherBlankOrZero[1]{%
  \romannumeral0\UD@CheckWhetherBlank{#1}{%
    \@firstoftwo{\expandafter}{} \@firstoftwo
  }{%
     \UD@zerofork{#1}%
     {\@firstoftwo{\expandafter}{} \@firstoftwo}%
     {\@firstoftwo{\expandafter}{} \@secondoftwo}%
  }%
}%
%%----------------------------------------------------------------------
%% \selectTask
%%......................................................................
\newcommand{\selectTask}[2]{%
  \UD@CheckWhetherBlankOrZero{#1}{%
    \UD@CheckWhetherBlankOrZero{#2}{% <blank or zero> = either spaces or a single "0" or no tokens at all
      \selectTaskA % #1 = #2 = <blank or zero>
    }{%
      \selectTaskB % #1 = <blank or zero>; #2 =/= <blank or zero>
    }%
  }{%
    \UD@CheckWhetherBlankOrZero{#2}{%
      \selectTaskC % #1 =/= <blank or zero>; #2 = <blank or zero>
    }{%
      \selectTaskD % #1 =/= <blank or zero>; #2 =/= <blank or zero>
    }%
  }%
}%
\newcommand{\selectTaskA}{%
  Task A---%
  \string##1 \textit{\textlangle blank or zero\textrangle } 
  and
  \string##2 \textit{\textlangle blank or zero\textrangle }%
  .%
}
\newcommand{\selectTaskB}{%
  Task B---%
  \string##1 \textit{\textlangle blank or zero\textrangle } 
  and
  \string##2 not \textit{\textlangle blank or zero\textrangle }%
  .%
}
\newcommand{\selectTaskC}{%
  Task C---%
  \string##1 not \textit{\textlangle blank or zero\textrangle } 
  and
  \string##2 \textit{\textlangle blank or zero\textrangle }%
  .%
}
\newcommand{\selectTaskD}{%
  Task D--- %
  \string##1 not \textit{\textlangle blank or zero\textrangle } 
  and
  \string##2 not \textit{\textlangle blank or zero\textrangle }%
  .%
}
\makeatother

\parindent=0pt
\parskip=\baselineskip
\addtolength\oddsidemargin{-1.5cm}
\addtolength\evensidemargin{-1.5cm}
\addtolength\textwidth{3cm}

\begin{document}

\verb*|\selectTask{0}{0}|: \selectTask{0}{0}\\
\verb*|\selectTask{  }{0}|: \selectTask{  }{0}\\
\verb*|\selectTask{0}{  }|: \selectTask{0}{  }\\
\verb*|\selectTask{  }{  }|: \selectTask{  }{  }\\
\verb*|\selectTask{}{0}|: \selectTask{}{0}\\
\verb*|\selectTask{0}{}|: \selectTask{0}{}\\
\verb*|\selectTask{}{}|: \selectTask{}{}\\
\verb*|\selectTask{}{  }|: \selectTask{}{  }\\
\verb*|\selectTask{  }{}|: \selectTask{  }{}

\verb*|\selectTask{0}{1}|: \selectTask{0}{1}\\
\verb*|\selectTask{  }{1}|: \selectTask{  }{1}\\
\verb*|\selectTask{}{1}|: \selectTask{}{1}

\verb*|\selectTask{1}{0}|: \selectTask{1}{0}\\
\verb*|\selectTask{1}{  }|: \selectTask{1}{  }\\
\verb*|\selectTask{1}{}|: \selectTask{1}{}

\verb*|\selectTask{1}{1}|: \selectTask{1}{1}

\textbf{BUT:}

\verb*|\selectTask{00}{00}|: \selectTask{00}{00}

\verb*|\selectTask{ 0 }{ 0 }|: \selectTask{ 0 }{ 0 }

\let\implicitzero=0%
\def\expandtospace{ }%
\verb*|\let\implicitzero=0|\\
\verb*|\def\myspace{ }|\\
\verb*|\selectTask{\implicitzero}{\implicitzero}|:\\ \selectTask{\implicitzero}{\implicitzero}

\verb*|\selectTask{\expandtospace}{\expandtospace}|:\\ \selectTask{\expandtospace}{\expandtospace}

\end{document}

在此处输入图片描述

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