Delphi		Each exception class must be derived from Exception class or from some of its descendant: type EMyException = class(Exception); EMyMathError = class(EMathError); Exception can be raised by raise reserved word: function Division(X,Y: Double): Double; begin Result:=0; if Y=0 then raise EMathError.Create('Division by zero') else Result:=X/Y; end; There are two ways to process exceptions: try...except and try...finally. The execution code must be placed between try and except. The exception handler code must be placed between except and end. try C:=A div B; except ShowMessage('Error!'); end; You can analyse the exception type in the handler code and use any exception object properties, like HelpContext and Message, inherited from base Exception class: try // some code here except on E: Exception do begin if E is EMathError then ShowMessage('Math error: '+E.Message); if E is EInOutError then ShowMessage('InOut error: '+E.Message); end; end; By default try...except suppresses the exception and if you want to pass it to the default exception handler, you have to reraise it: try // some code here except on E.Exception do LogMemo.Lines.Add(E.Message); raise; end; Any unhandled exceptions passed to the Application exception handler. This handler calls OnException event then shows the error message box. If you want to execute some code independently of exceptions which can occur, just use try...finally construction. Code please into the finally block will be always executed independently from raised exceptions: ClientList:=TList.Create; try // working with ClientList finally // try...finally guarantees that this code will be executed, // so the ClientList object will be always destroyed ClientList.Free; end; Of course, you can combine try...except and try..finally: ClientList:=TList.Create; try try // working with ClientList except // suppress exception and add error message to log on E.Exception do LogMemo.Lines.Add(E.Message); end; finally // try...finally guarantees that this code will be executed, // so the ClientList object will be always destroyed ClientList.Free; end;
C#		A try block used to partition code that may be affected by an exception, and catch blocks are used to handle any resulting exceptions. A finally block can be used to execute code regardless of whether an exception is thrown. A throw used to generate exception. All exception derived from System.Exception. void Func() { try { throw new ArgumentNullException(); } catch(System.Exception e) { } finally { } } A try statement without a catch or finally block will result in a compiler error. You can reraise exception: catch(System.Exception e) { throw e; } or if use parameterless catch block catch { throw; }      catch and finally can be used simultaneously in one try block.