Syntax

var ErrorProc: Pointer;

procedure MyErrorProc(ErrorCode: Integer; ErrorAddr: Pointer);
begin
  ...
end;
ErrorProc := @MyErrorProc;

Description

When a runtime error occurs, and the ErrorProc variable is not nil, Delphi calls the procedure that ErrorProc points to. The procedure takes two arguments: the error number and the error address.

If ErrorProc is nil, Delphi calls RunError to issue an error message and halt the program. In a GUI application, Delphi shows the error message in a dialog box. In a console application, Delphi prints the error message to the console.

Delphi stores the error code for I/O errors separately. If ErrorCode is zero, most likely the error is an I/O error. Call IOResult to obtain the I/O error code.

Example

// Log errors in an application event log (in Windows NT).
procedure LogError(ErrorCode: Integer; ErrorAddr: Pointer);
var
  ApplicationName: string;
  Handle: THandle;
  Strings: array[0..0] of PChar;
begin
  // Change the application path to its base name, e.g., 'App'.
  // The application must have created the appropriate register key.
  ApplicationName := ChangeFileExt(ExtractFileName(ParamStr(0)), ''),
  Handle := RegisterEventSource(nil, PChar(ApplicationName));

  if ErrorCode = 0 then
    ErrorCode := IOResult;

  // Get the exception message.
  Strings[0] := PChar('Runtime error #' + IntToStr(ErrorCode));

  // Define the Category elsewhere.
  ReportEvent(Handle, EventLog_Error_Type, Category, ErrorCode,
    nil, 0, 1, @Strings, nil);

  DeregisterEventSource(Handle);
end;
...
ErrorProc := @LogError;

See Also