diff --git a/calc.cpp b/calc.cpp
deleted file mode 100644
index ab15a47..0000000
--- a/calc.cpp
+++ /dev/null
@@ -1,30 +0,0 @@
-/* Translation of calc.c example to C++
-   (the "-goal true" in the following turns off the banner)
-
-   swipl-ld -o calc -goal true calc.cpp calc.pl && ./calc 1 + 2 + 3
- */
-
-#include <string>
-#include <SWI-cpp2.h>
-
-int main(int argc, char **argv) {
-
-  PlEngine e(argv[0]);
-
-  // combine all the arguments in a single string
-  std::string expression;
-  for (int n = 1; n < argc; n++) {
-    if (n != 1) {
-      expression.append(" ");
-    }
-    expression.append(argv[n]);
-  }
-
-  // Lookup calc/1 and make the arguments and call
-
-  PlPredicate pred("calc", 1, "user");
-  PlTerm_string h0(expression);
-  PlQuery q(pred, PlTermv(h0));
-
-  return PlWrap<int>(q.next_solution()) ? 0 : 1;
-}
diff --git a/calc.pl b/calc.pl
deleted file mode 100644
index b5e6ca9..0000000
--- a/calc.pl
+++ /dev/null
@@ -1,5 +0,0 @@
-calc(Atom) :-
-        term_to_atom(Expr, Atom),
-        A is Expr,
-        write(A),
-        nl.
diff --git a/pl2cpp.plx b/pl2cpp.plx
index 609f640..822ed4e 100644
--- a/pl2cpp.plx
+++ b/pl2cpp.plx
@@ -239,11 +239,26 @@ rewritten in C++. As before, it is compiled by
   swipl-ld -o calc -goal true calc.cpp calc.pl
 \end{code}
 
+The Prolog file is simple:
+
+\begin{code}
+calc(String) :-
+    term_string(Expr, String),
+    A is Expr,
+    writeln(A).
+\end{code}
+
+The C part of the application parses the command line options,
+initialises the Prolog engine, locates the \verb$calc/1$ predicate and calls
+it.  The code is in \figref{calccpp}.
+
+\begin{figure}
 \begin{code}
 #include <string>
 #include <SWI-cpp2.h>
 
-int main(int argc, char **argv) {
+int
+main(int argc, char **argv) {
 
   PlEngine e(argv[0]);
 
@@ -265,6 +280,9 @@ int main(int argc, char **argv) {
   return PlWrap<int>(q.next_solution()) ? 0 : 1;
 }
 \end{code}
+\caption{C++ source for the calc application}
+\label{fig:calccpp}
+\end{figure}
 
 \section{Sample code}
 \label{sec:cpp2-sample-code}