This symbol (an integral sign, ‘crossed’) does not appear in any of the fonts ordinarily available to (La)TeX users, but it can be created by use of the following macros:
\def\Xint#1{\mathchoice
{\XXint\displaystyle\textstyle{#1}}%
{\XXint\textstyle\scriptstyle{#1}}%
{\XXint\scriptstyle\scriptscriptstyle{#1}}%
{\XXint\scriptscriptstyle\scriptscriptstyle{#1}}%
\!\int}
\def\XXint#1#2#3{{\setbox0=\hbox{$#1{#2#3}{\int}$}
\vcenter{\hbox{$#2#3$}}\kern-.5\wd0}}
\def\ddashint{\Xint=}
\def\dashint{\Xint-}
\dashint gives a single-dashed integral sign, \ddashint a
double-dashed one.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=prinvalint