如何在 \fbox 中获取换行符？

Question

我尝试在里面放两行\fbox，但没有成功。下面是我的代码

\documentclass{beamer}
\usepackage{vietnam}
\begin{document}
\begin{frame}
\frametitle{Exhaustive Search}
{\centering\fbox{ One billion searches per second $\Rightarrow 36 yrs \newline All this to recover only $10$ bits !}}
\end{frame}
\end{document}

Answer 1

A\fbox不允许换行。但是，您有几种可能性：

在 内使用 a \parbox（或 a minipage）\fbox：

\documentclass{beamer}
\usepackage{vietnam}
\begin{document}
\begin{frame}
\frametitle{Exhaustive Search}
\fbox{\parbox{\dimexpr\linewidth-2\fboxsep-2\fboxrule\relax}{\centering One billion searches per second $\Rightarrow$ 36 yrs  \\ All this to recover only $10$ bits !}}%
\end{frame}
\end{document}

在里面\fbox，如果您希望宽度自动调整，请使用包varwidth中的环境：varwidth

\documentclass{beamer}
\usepackage{vietnam}
\usepackage{varwidth}

\begin{document}
\begin{frame}
\centering
\fbox{\begin{varwidth}{\textwidth}
\centering
One billion searches per second $\Rightarrow$ 36 yrs  \\ All this to recover only $10$ bits !
\end{varwidth}}
\end{frame}
\end{document}

或者使用以下定义的框tcolorbox：

\documentclass{beamer}
\usepackage{vietnam}
\usepackage[most]{tcolorbox}
\tcbuselibrary{fitting}

\begin{document}
\begin{frame}
\frametitle{Exhaustive Search}
\begin{tcolorbox}[minipage,colback=white,arc=0pt,outer arc=0pt]
\centering
One billion searches per second $\Rightarrow$ 36 yrs \\ All this to recover only $10$ bits !
\end{tcolorbox}
\end{frame}
\end{document}

\node或者使用带有密钥的TikZ align：

\documentclass{beamer}
\usepackage{vietnam}
\usepackage{tikz}

\begin{document}
\begin{frame}
\frametitle{Exhaustive Search}
\centering
\tikz
  \node[draw,align=center]
  {One billion searches per second $\Rightarrow$ 36 yrs \\ All this to recover only $10$ bits !};
\end{frame}
\end{document}

或者...

Answer 2

如果您要插入手动换行符，您也可以构造一个tabular：

\documentclass{beamer}
\begin{document}
\begin{frame}
  \frametitle{Exhaustive Search}
  \centering
  \fbox{\begin{tabular}{@{}c@{}}
    One billion searches per second $\Rightarrow 36$ yrs \\
    All this to recover only $10$ bits !
  \end{tabular}}
\end{frame}
\end{document}

...或者使用纯粹的tabular方法：

\documentclass{beamer}
\begin{document}
\begin{frame}
  \frametitle{Exhaustive Search}
  \centering
  \begin{tabular}{|c|}
    \hline
    One billion searches per second $\Rightarrow 36$ yrs \\
    All this to recover only $10$ bits ! \\
    \hline
  \end{tabular}
\end{frame}
\end{document}