examples: don't promote unchecked function calls

* etc/bench.pl.in, examples/c/bistromathic/parse.y,
* examples/c/calc/calc.y, examples/c/pushcalc/calc.y: Check scanf's
return value.
* doc/bison.texi: Likewise, but only for the second example, to avoid
cluttering the very simple case.

1 files changed, 2 insertions, 1 deletions

diff --git a/etc/bench.pl.in b/etc/bench.pl.in
index b7d44f41..036bf52e 100755
--- a/etc/bench.pl.in
+++ b/etc/bench.pl.in
@@ -498,7 +498,8 @@ yylex (void)
     case '5': case '6': case '7': case '8': case '9':
       {
         int nchars = 0;
-        sscanf (input - 1, "%d%n", &yylval.NUM, &nchars);
+        int n = sscanf (input - 1, "%d%n", &yylval.NUM, &nchars);
+        assert (n == 1);
         input += nchars - 1;
         return NUM;
       }