How do you display straight quotes instead of curly quotes when using LaTeX's 'listings' package?

Question

I'm using LaTeX's "listings" package to format source code. Unfortunately I get curly quotes instead of straight quotes. Since the curly quotes don't always point in the right direction, it looks bad. How can I get straight quotes instead?

I'd prefer not to change or filter the source code itself. Filtering the code to properly change " to `` or '' would work, but this is easier done than said with multiple quotes on a line, or quotes spanning multiple lines. Or you could use symbol or a host of other things. But I'd really like to keep the source unchanged.

Example LaTeX:

\documentclass{article} \usepackage{listings} \begin{document} \begin{lstlisting} Fahrenheit=input("What is the Fahrenheit temperature?") Celsius=(5.0/9.0)*(Fahrenheit-32) print"The temperature is",Celsius,"degrees Celsius" \end{lstlisting} \end{document} 

Example output (using Miktex on windows):

(Direct link to image of incorrect output)

Answer 1

I see in the documentation (which should have been distributed with the packge, but is available at http://www.ctan.org/tex-archive/macros/latex/contrib/listings/listings.pdf) for listings that there is a settable property called upquote to take care of this.

From the documentation:

upquote=⟨true|false⟩                                                false   determines whether the left and right quote are printed ‘’ or `'. This    key requires the textcomp package if true.  

Do something like

\lstset{upquote=true} 

before begining the list environment, or use

\begin{lstlisting}[upquote=true] ... \end{lstlisting} 

---

It is also possible that tis property is already set for you in the appropriate language definition (see the docs again, big list of predefined languages on page 12).

Use:

\lstloadlanguages{<dialects you need>} 

in the header. And then set the language using either of the above conventions for choosing options.