计算宏参数中的行数

Question

是否可以定义一个命令，根据其参数文本是否占用多行来采取不同的操作？

我希望如果文本块只有一行则居中，否则两端对齐。

Answer 1

像这样吗？

\documentclass{article}

\usepackage[showframe]{geometry}% just to make it easy to see the effect

\makeatletter
\def\centerorjustify#1{%
  \setbox\@tempboxa\hbox{#1}%
  \ifdim\wd\@tempboxa>\linewidth
    #1%
  \else
    \begin{center}%
      #1%
    \end{center}%
  \fi
}

\begin{document}

\centerorjustify{Hello}

\centerorjustify{Hello world}

\centerorjustify{A long text that will be a little shorter than the text width.}

\centerorjustify{A longer text that will be longer than a line so that we can see the effect of the macro. Yeah, I don't know what else to type in here}

\end{document}

该宏将内容放入其中，\hbox并将其宽度与之进行比较，\linewdith如果较短则将其居中。

Answer 2

只是为了好玩：

你可能会误用 caption 包来实现类似的行为

\documentclass{article}

\usepackage{caption}
\usepackage{newfloat}

\DeclareCaptionFormat{empty}{#3}
\DeclareFloatingEnvironment{my}
\captionsetup[my]{format=empty}

\begin{document}

\captionof{my}{one line}

\captionof{my}{longt text over multiple lines with much longer text and even longer text so that it stretches over multiple lines}

\end{document}