Enhancement - Date::toISO

- Added ISO date format support (19980119T070000Z) to Date class, for use
  in export.ical.
- Added unit test.

src/Date.cpp

@@ -25,6 +25,7 @@
 //
 ////////////////////////////////////////////////////////////////////////////////
 #include <iostream>
+#include <iomanip>
 #include <sstream>
 #include <time.h>
 #include <assert.h>
@@ -375,6 +376,25 @@ std::string Date::toEpochString ()
   return epoch.str ();
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// 19980119T070000Z =  YYYYMMDDThhmmssZ
+std::string Date::toISO ()
+{
+  struct tm* t = gmtime (&mT);
+
+  std::stringstream iso;
+  iso << std::setw (4) << std::setfill ('0') << t->tm_year + 1900
+      << std::setw (2) << std::setfill ('0') << t->tm_mon + 1
+      << std::setw (2) << std::setfill ('0') << t->tm_mday
+      << "T"
+      << std::setw (2) << std::setfill ('0') << t->tm_hour
+      << std::setw (2) << std::setfill ('0') << t->tm_min
+      << std::setw (2) << std::setfill ('0') << t->tm_sec
+      << "Z";
+
+  return iso.str ();
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 void Date::toEpoch (time_t& epoch)
 {

src/Date.h

@@ -47,6 +47,7 @@ public:
   void toEpoch (time_t&);
   time_t toEpoch ();
   std::string toEpochString ();
+  std::string toISO ();
   void toMDY (int&, int&, int&);
   const std::string toString (const std::string& format = "m/d/Y") const;
   const std::string toStringWithTime (const std::string& format = "m/d/Y") const;

src/tests/date.t.cpp

@@ -34,7 +34,7 @@ Context context;
 ////////////////////////////////////////////////////////////////////////////////
 int main (int argc, char** argv)
 {
-  UnitTest t (143);
+  UnitTest t (144);
 
   try
   {
@@ -150,6 +150,9 @@ int main (int argc, char** argv)
     Date fromEpoch (epoch.toEpoch ());
     t.is (fromEpoch.toString (), epoch.toString (), "ctor (time_t)");
 
+    Date iso (1000000000);
+    t.is (iso.toISO (), "20010909T014640Z", "1,000,000,000 -> 20010909T014640Z");
+
     // Date parsing.
     Date fromString1 ("1/1/2008");
     t.is (fromString1.month (),   1, "ctor (std::string) -> m");