How to enter symbol for inexact differential in xelatex?

Question

The LaTeX symbol list document recommends this:

\def\dbar{{\mathchar’26\mkern-12mu d}}

Compiling this gives an error about mathcar being undefined.

A minimal example follows:

\documentclass[a4paper,11pt]{scrbook}
\def\dbar{{\mathchar’26\mkern-12mu d}}

\author{asd}
\title{asd}
\begin{document}
\maketitle

$\dbar Q = d U + \dbar W$

\end{document}

Answer 1

Works fine for me

\documentclass{article}
\def\dbar{{\mathchar'26\mkern-12mu d}}
\begin{document}
abc $\dbar$
\end{document}

Answer 2

Since you mention xelatex in your question I assume that you want a unicode-type solution to your problem.

This works for me:

\documentclass{article}
\usepackage{amsmath}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\begin{document}
đ $\text{đ}$
\end{document}