added files particular to portable_archive

doc/tutorial/code/tutorial_pba_7.cpp

@@ -0,0 +1,54 @@
+/** tutorial_pba_7.cpp
+ *
+ * (C) Copyright 2011 François Mauger, Christian Pfligersdorffer
+ *
+ * Use, modification and distribution is subject to the Boost Software
+ * License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+ * http://www.boost.org/LICENSE_1_0.txt)
+ *
+ */
+
+/**
+ * The intent of this program is to serve as a tutorial for
+ * users of the portable binary archive in the framework of 
+ * the Boost/Serialization library. 
+ *
+ * This example shows how the default behaviour of standard 
+ * I/O streams does not support the read/write operations of 
+ * non-finite floating point values in a portable way.
+ *
+ */
+
+#include <string>
+#include <iostream>
+#include <sstream>
+#include <limits>
+
+using namespace std;
+
+int main (void)
+{
+  {
+    float x = numeric_limits<float>::infinity ();
+    double y = numeric_limits<double>::quiet_NaN ();
+    cout.precision (8);
+    cout << "x = " << x << endl;
+    cout.precision (16);
+    cout << "y = " << y << endl;
+  }
+
+  {
+    string input ("inf nan");
+    istringstream iss (input);
+    float x; 
+    double y;
+    iss >> x >> y;
+    if (! iss)
+      {
+	cerr << "Cannot read 'x' or 'y' : non finite values are not supported !" << endl;
+      }
+  }
+  return 0;
+}
+
+// end of tutorial_pba_7.cpp