Very long name of Section reflects badly in TOC

Question

I have too long name of Section that reflects badly in TOC.

Name of section doesn't have spaces in its name.

I can not know how pledge it to move part of name to the next line automatically.

(Idea to split name manually is bad).

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---

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 \begin{document}
 \tableofcontents
 \part{New Part}
 \chapter{Name of the Chapter}

%Can not fit on the page, and can not be divided automatically
 \section{This\_Is\_very\_Long\_Name\_of\_Section\_That\_Can\_Not\_Fit\_On\_Page\_And\_Push\_Out\_Of\_The\_Page\_Field}
 \section{This\_Is\_very\_Long\_Name\_of\_Section \ That\_Have\_Spaces On\_Its Name \ And\_Will\_Be Bring\_On\_The\_Next\_Line}

 \end{document}

Also, name of section creates automatically, and I previously cannot know how long will be it.

Answer 1

Use \_\protect\linebreak[0] instead of \_ then it will allow (but not encourage) breaking after the _

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Or if you want to allow the lines to fall short at the breaks,

\def\myunderscore{\_\nobreak\hfil\protect\penalty0\hfilneg}
\tableofcontents

\section{abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz\myunderscore abcxyz}