How does one display straight quotes in the normal font?

Question

From this code:

\subsubsection{General Escaping Format}
Generally, escaping MUST be done in a manner similar to most programming
languages, such as C, C++, Java, or similar, for quoted string escapes. Such an
escaping scheme is defined by three characters: a starting delimiter, a
termination delimiter, and an escape character. For instance, in C, the starting
delimiter is the quote mark, ", the ending delimiter is also a quote
mark ", and the escape character is the backslash \textbackslash.

XeTeX gives this:

Note in particular the quotes that I want to be raw C style " characters, are converted into a pair of right curly quotes. Of course, I'm talking about programming languages in this section, so I need the quotes to be displayed as typewriter style straight quotes. I can force the straight quotes if I use \verb, but this causes the quotes to look strange because the actual font is different.

Answer 1

You can use \textquotedbl with

\usepackage[T1]{fontenc}% http://ctan.org/pkg/fontenc

Here is a display of the output:

\documentclass{article}
\usepackage[T1]{fontenc}% http://ctan.org/pkg/fontenc
\begin{document}
\setcounter{section}{3}\setcounter{subsection}{1}% Just for this example
\subsubsection{General Escaping Format}
Generally, escaping MUST be done in a manner similar to most programming
languages, such as C, C++, Java, or similar, for quoted string escapes. Such an
escaping scheme is defined by three characters: a starting delimiter, a
termination delimiter, and an escape character. For instance, in C, the starting
delimiter is the quote mark, \textquotedbl, the ending delimiter is also a quote
mark \textquotedbl, and the escape character is the backslash \textbackslash.
\end{document}

Answer 2

The problem is in the Ligatures=TeX option that is automatically added when you say only

\usepackage{fontspec}

so using the Latin Modern fonts. If you redefine the font without the option, then typing " will give straight quotes. So

\usepackage{fontspec}
\setmainfont{Latin Modern Roman}

If however you want to keep the other "traditional ligatures", you can make a copy of text-tex.map, call it text-tex-sq.map (for instance), and modify it to read as

; TECkit mapping for TeX input conventions <-> Unicode characters

LHSName "TeX-text"
RHSName "UNICODE"

pass(Unicode)

; ligatures from Knuth's original CMR fonts
U+002D U+002D                   <>      U+2013  ; -- -> en dash
U+002D U+002D U+002D    <>      U+2014  ; --- -> em dash

U+0027                  <>      U+2019  ; ' -> right single quote
U+0027 U+0027   <>      U+201D  ; '' -> right double quote
;U+0022                   >      U+201D  ; " -> right double quote ; no change!

U+0060                  <>      U+2018  ; ` -> left single quote
U+0060 U+0060   <>      U+201C  ; `` -> left double quote

U+0021 U+0060   <>      U+00A1  ; !` -> inverted exclam
U+003F U+0060   <>      U+00BF  ; ?` -> inverted question

; additions supported in T1 encoding
U+002C U+002C   <>      U+201E  ; ,, -> DOUBLE LOW-9 QUOTATION MARK
U+003C U+003C   <>      U+00AB  ; << -> LEFT POINTING GUILLEMET
U+003E U+003E   <>      U+00BB  ; >> -> RIGHT POINTING GUILLEMET

Compile with teckit_compile tex-text-sq.map and keep the text-text-sq.tec file that will be produced in the same directory as your file: now the call

\usepackage{fontspec}
\setmainfont[Mapping=tex-text-sq]{Latin Modern Roman}

will give the "traditional ligatures" but keep straight double quotes straight.