simple utility function usable by several boost tools

[SVN r34791]

tools/common/time_string.hpp

@@ -0,0 +1,49 @@
+// ---- time_string: thin wrapper around std::strftime    -------- //
+//
+//            Copyright Gennaro Prota 2006
+//
+// Distributed under 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)
+
+#ifndef BOOST_TIME_STRING_HPP_GP_20060731
+#define BOOST_TIME_STRING_HPP_GP_20060731
+
+#include <string>
+#include <ctime>
+
+namespace boost {
+
+// Many of the boost tools just need a quick way to obtain
+// a formatted "run date" string or similar. This is one.
+//
+// In case of failure false is returned and result is
+// unchanged.
+//
+inline
+bool time_string(std::string & result
+               , const std::string & format = "%X UTC, %A %d %B %Y")
+{
+    // give up qualifying names and using std::size_t,
+    // to avoid including "config.hpp"
+    using namespace std;
+
+    const int sz = 256;
+    char buffer [ sz ] = { 0 };
+    const time_t no_cal_time ( -1 );
+    time_t tod;
+
+    const bool ok =
+        time ( &tod ) != no_cal_time
+     && strftime( buffer, sz, format.c_str(), gmtime( &tod ) ) != 0
+        ;
+
+    if (ok)
+        result = buffer;
+
+    return ok;
+}
+
+}
+
+#endif // include guard