[istream.sentry] Minor tweaks

Author: cpplearner

source/iostreams.tex

@@ -4571,7 +4571,7 @@
 that are part of the library.
 The semantics of the constructor used in user code is as specified.
 \end{footnote}
-If \tcode{noskipws} is zero and
+If \tcode{noskipws} is \tcode{false} and
 \tcode{is.flags() \& ios_base::skipws}
 is nonzero, the function extracts and discards each character as long as
 the next available input character \tcode{c} is a whitespace character.
@@ -4600,8 +4600,8 @@
 To decide if the character \tcode{c} is a whitespace character,
 the constructor performs as if it executes the following code fragment:
 \begin{codeblock}
-const ctype<charT>& ctype = use_facet<ctype<charT>>(is.getloc());
-if (ctype.is(ctype.space, c) != 0)
+const ctype<charT>& ct = use_facet<ctype<charT>>(is.getloc());
+if (ct.is(ct.space, c))
   // \tcode{c} is a whitespace character.
 \end{codeblock}
 
@@ -4610,7 +4610,7 @@
 \tcode{is.good()}
 is
 \tcode{true},
-\tcode{\exposid{ok_} != false}
+\tcode{\exposid{ok_} != false};
 otherwise,
 \tcode{\exposid{ok_} == false}.
 During preparation, the constructor may call