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[expr.add] Simplify wording for pointer subtraction #8565

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[expr.add] Simplify wording for pointer subtraction #8565

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11 changes: 6 additions & 5 deletions source/expressions.tex
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Original file line number Diff line number Diff line change
Expand Up @@ -7206,13 +7206,10 @@
\indextext{\idxcode{ptrdiff_t}}%
\indextext{comparison!undefined pointer}%
When two pointer expressions \tcode{P} and \tcode{Q} are subtracted,
the type of the result is an \impldef{type of \tcode{ptrdiff_t}} signed
integral type; this type shall be the same type that is named by
\tcode{std::ptrdiff_t} in the \libheader{cstddef}
header\iref{support.types.layout}.
the result is a prvalue of type \tcode{std::ptrdiff_t}.
\begin{itemize}
\item If \tcode{P} and \tcode{Q} both evaluate to null pointer values,
the result is 0.
the value is 0.
\item Otherwise, if \tcode{P} and \tcode{Q} point to, respectively,
array elements $i$ and $j$
of the same array object \tcode{x},
Expand All @@ -7225,6 +7222,10 @@
\end{note}
\item Otherwise, the behavior is undefined.
\end{itemize}
\begin{note}
The \grammarterm{typedef-name} \tcode{std::ptrdiff_t} is declared in the standard header
\libheader{cstddef}\iref{cstddef.syn,support.types.layout}.
\end{note}

\pnum
For addition or subtraction, if the expressions \tcode{P} or \tcode{Q} have
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