How to align left and right on the same lines

Question

the first c program

I'm trying to create something similar to this, but I am having trouble getting it to work. I have tried using the tabular environment, but i get an "overfull hbox". I have also used tabulary and \hfill. \hfill seems like what I want, but I am having trouble using it across multiple lines. What would be the best way to implement something like the picture in LaTeX?

Here is what i have tried so far:

\verb|#include <stdio.h> \hfill \verb{include information about standard library}
\verb|main| \hfill \emph{define a function named} \verb|main| \emph{that receives no argument values}

and so on, but once the italic text on the right gets too long, it starts to align against the left margins.

Welcome to the TeX.SE. Can you add your work, please? – Sebastiano Dec 23 '16 at 18:34 — Sebastiano, Dec 23 '16 at 18:34

score 6 · Accepted Answer · answered Dec 23 '16 at 19:19

Here is a suggestion using listings.

\documentclass{article}
\usepackage{listings}
\lstset{
  language=C,
  frame=tb,
  escapeinside={@:}{:@},
  showstringspaces=false,
  basicstyle=\ttfamily
}

\newcommand\Comment{\hfill\normalfont\itshape}
\begin{document}

\begin{lstlisting}[caption={First C code}]
#include <stdio.h> @:\Comment include information about standard library:@

main() @:\Comment define a function named \texttt{main} :@
@:\Comment that receives no argument values :@
{
    printf("hello world\n");
}

\end{lstlisting}
\end{document}

score 4 · Answer 2 · answered Dec 23 '16 at 20:47

A variant of Torbjørn's answer, where we can decide the comment box has no height (but some manual adjustment may become necessary).

\documentclass{article}
\usepackage{xparse}
\usepackage{listings}
\lstset{
  language=C,
  frame=tb,
  escapeinside={@:}{:@},
  showstringspaces=false,
  basicstyle=\linespread{1.4}\ttfamily,
  columns=fullflexible,
}

\NewDocumentCommand{\Comment}{O{\depth}m}{%
  \hfill\normalfont\itshape
  \renewcommand{\arraystretch}{0.7}%
  \raisebox{0pt}[\height][#1]{%
    \begin{tabular}[t]{@{}r@{}}
    #2
    \end{tabular}%
  }%
}
\DeclareTextFontCommand{\textttup}{\upshape\ttfamily}
\newcommand{\escape}[1]{\textttup{\symbol{`\\}#1}}

\begin{document}

\begin{lstlisting}[caption={First C code}]
#include <stdio.h>     @:\Comment{include information about standard library}:@
main()                 @:\Comment{define a function named \textttup{main}\\
                                  that receives no argument values}:@
{                      @:\Comment{statements of \textttup{main} are enclosed in braces}:@
    printf("hello world\n"); @:\Comment[0pt]{\textttup{main} calls library function \textttup{printf}\\
                                             to print the sequence of characters;\\
                                             \escape{n} represents the newline character}:@
}
@:\vspace{-.5\baselineskip}:@
\end{lstlisting}
\end{document}

Werner · Answer 3 · 2016-12-23T19:25:15.213

Below I've set the code inside a figure (to allow it to float, if needed), while the structure is defined inside a tabular.

\documentclass{article}

% Insert a code comment: \codecomment{<comment>}
% Comment is set in a [t]op-aligned tabular that has tight
% vertical spacing and also overlaps with content below it.
\newcommand{\codecomment}[1]{{%
  \renewcommand{\arraystretch}{0}%
  \normalfont\itshape\hfill
  \smash{\begin{tabular}[t]{r @{}}
    #1%
  \end{tabular}}%
}}
\newcommand{\codefont}{\normalfont\ttfamily}
\newcommand{\setcode}[1]{{\codefont #1}}

\begin{document}

\begin{figure}
  \renewcommand{\arraystretch}{1.5}% Space code vertically (http://tex.stackexchange.com/a/31704/5764)
  \codefont% Set code font
  \begin{tabular}{p{\dimexpr\linewidth-2\tabcolsep}}
    \hline \\
    \string#include <stdio.h>
      \codecomment{include information about standard library} \\
    main()
      \codecomment{define a function named \setcode{main} \\
                   that receives no argument values} \\
    \string{
      \codecomment{statements of \setcode{main} are enclosed in braces} \\
    \qquad printf("hello, world\string\n");
      \codecomment{\setcode{main} calls library function \setcode{printf} \\
                   to print this sequence of characters; \\
                   \setcode{\string\n} represents the newline character} \\
    \string} \\\\
    \multicolumn{1}{c}{\normalfont A first C program.} \\
    \hline
  \end{tabular}
\end{figure}

\end{document}

Hi Werner my congratulations for your solution. My answer is not very good, — Sebastiano, Dec 23 '16 at 19:17
I would comment the line end #1% in the definition of \codecomment, because the tabular code only adds one \unskip. If the user leaves a space before the closing argument brace, then only one space would be removed and the comment is moved by one space to the left. — Heiko Oberdiek, Dec 23 '16 at 19:22

How to align left and right on the same lines

3 Answers3