diff -r caf16813b1e8 -r 1782aa72495a lemon/lp_base.h
--- a/lemon/lp_base.h	Sat Jul 21 10:18:57 2012 +0200
+++ b/lemon/lp_base.h	Fri Jul 20 17:09:01 2012 +0200
@@ -1007,6 +1007,36 @@
 
   public:
 
+    ///\e
+    class UnsupportedFormatError : public Exception
+    {
+      std::string _format;
+      mutable std::string _what;
+    public:
+      explicit UnsupportedFormatError(std::string format) throw()
+        : _format(format) { }
+      virtual ~UnsupportedFormatError() throw() {}
+      virtual const char* what() const throw() {
+        try {
+          _what.clear();
+          std::ostringstream oss;
+          oss << "lemon::UnsupportedFormatError: " << _format;
+          _what = oss.str();
+        }
+        catch (...) {}
+        if (!_what.empty()) return _what.c_str();
+        else return "lemon::UnsupportedFormatError";
+      }
+    };
+    
+  protected:
+    virtual void _write(std::string, std::string format) const
+    {
+      throw UnsupportedFormatError(format);
+    }
+    
+  public:
+
     /// Virtual destructor
     virtual ~LpBase() {}
 
@@ -1555,12 +1585,27 @@
     ///Set the sense to maximization
     void min() { _setSense(MIN); }
 
-    ///Clears the problem
+    ///Clear the problem
     void clear() { _clear(); rows.clear(); cols.clear(); }
 
-    /// Sets the message level of the solver
+    /// Set the message level of the solver
     void messageLevel(MessageLevel level) { _messageLevel(level); }
 
+    /// Write the problem to a file in the given format
+
+    /// This function writes the problem to a file in the given format.
+    /// Different solver backends may support different formats.
+    /// Trying to write in an unsupported format will trigger
+    /// \ref UnsupportedFormatError. For the supported formats,
+    /// visit the documentation of the base class of the related backends
+    /// (\ref CplexBase, \ref GlpkBase etc.)
+    /// \param file The file path
+    /// \param format The output file format.
+    void write(std::string file, std::string format = "MPS") const
+    {
+      _write(file.c_str(),format.c_str());
+    }
+
     ///@}
 
   };