How can I do this symbol (integral with a barre) in latex? [duplicate]

Question

How can I do this symbole in latex ? (if possible with the barre of the middle more straight).

Answer 1

Some fonts have such an integral sign built in, but if not, you can always stack a - or $-$ over one.

\documentclass{article}
\usepackage{stackengine}
\stackMath
\begin{document}
$\stackinset{c}{}{c}{}{\mkern1.5mu\mbox{-}}{\int}x\,dx$
$\displaystyle\stackinset{c}{}{c}{}{-\mkern4mu}{\displaystyle\int_0^t}x\,dx$
\end{document}

Built in examples include versions with a slanted bar (denoted \fint) as well as some versions with a horizontal bar.

Those packages with a slanted \fint include: txfonts, pxfonts, esint, and stix.

Versions with a horizontal bar include:

1. \strokedint from the MnSymbol package, and

2. \intbar from the stix package.

Answer 2

The symbol already exists in esint:

\documentclass[ a4paper]{article}
\usepackage{mathtools}
\usepackage{esint}

\newcommand*{\dd}{\mathop{}\!\mathrm{d}}

\begin{document}

\[ \fint_{\partial\mathrlap{B_{R}}}u(y)\dd y \]%

\end{document}