When I use columns=fixed to present my listings, the letters are spaced too far apart. Why is that?
\documentclass{article}
\usepackage{listings}
\lstset{columns=fixed, basicstyle=\ttfamily}}
\begin{document}
\begin{lstlisting}
Hello, world!
\end{lstlisting}
\end{document}
The problem, as user egreg has previously pointed out, is that
the default setting of listings with "fixed columns" has a space 0.6em wide, while the characters in Computer Modern Typewriter are 0.5em wide. Fixed Width Font with LTXexample environment
One can use the basewidth key to fix this.
\documentclass{article}
\usepackage{listings}
\lstset{columns=fixed, basicstyle=\ttfamily, basewidth=0.5em}
\begin{document}
\begin{lstlisting}
Hello, world!
\end{lstlisting}
\end{document}
The answer linked above also provides a more flexible solution that works regardless of which monospaced font you use.
