[istream.extractors,stringbuf.members] Add spaces around operator - (#7816)

Author: Andreas-Krug

Diff for: source/iostreams.tex

@@ -4948,7 +4948,7 @@
 \pnum
 Characters are extracted and stored until any of the following occurs:
 \begin{itemize}
-\item \tcode{n-1} characters are stored;
+\item \tcode{n - 1} characters are stored;
 \item end of file occurs on the input sequence;
 \item letting \tcode{ct} be \tcode{use_facet<ctype<charT>>(in.getloc())},
 \tcode{ct.is(ct.space, c)} is \tcode{true}.
@@ -8530,9 +8530,9 @@
 the \tcode{basic_stringbuf}'s underlying character sequence in \tcode{buf}:
 \begin{itemize}
 \item If \tcode{ios_base::out} is set in \exposid{mode},
-  then \tcode{sv(pbase(), high_mark-pbase())} is returned.
+  then \tcode{sv(pbase(), high_mark - pbase())} is returned.
 \item Otherwise, if \tcode{ios_base::in} is set in \exposid{mode},
-  then \tcode{sv(eback(), egptr()-eback())} is returned.
+  then \tcode{sv(eback(), egptr() - eback())} is returned.
 \item Otherwise, \tcode{sv()} is returned.
 \end{itemize}