Download [DD] Delphi Developer Certification Exam Preparation Guide and more Exams Technology in PDF only on Docsity!
Preparation Guide
Question 1. Which Delphi directive tells the compiler to include a unit only if a specific symbol is defined? A) {$INCLUDE} B) {$IFDEF} C) {$DEFINE} D) {$ELSE} Answer: B Explanation: {$IFDEF SYMBOL} ... {$ENDIF} includes code only when SYMBOL is defined. Question 2. In a Delphi unit, which section is compiled first? A) implementation B) interface C) initialization D) finalization Answer: B Explanation: The interface section is processed before implementation, allowing other units to see its declarations. Question 3. What is the default string type in modern Delphi versions? A) AnsiString B) ShortString C) UnicodeString D) WideString Answer: C Explanation: Since Delphi 2009, UnicodeString (UTF-16) is the default string type.
Preparation Guide
Question 4. Which of the following integer types always occupies 4 bytes regardless of platform? A) ShortInt B) Integer C) Int D) NativeInt Answer: B Explanation: Integer is a 32-bit signed type on both 32- and 64-bit platforms. Question 5. How do you declare a constant array of three integers with values 10, 20, 30? A) const Numbers: array[0..2] of Integer = (10,20,30); B) const Numbers: array of Integer = [10,20,30]; C) const Numbers = (10,20,30); D) const Numbers: array[1..3] of Integer = (10,20,30); Answer: A Explanation: The syntax uses a static array range and parentheses for initialization. Question 6. Which keyword is used to declare a variable that is shared among all threads in a Delphi program? A) threadvar B) varthread C) shared D) volatile Answer: A
Preparation Guide
D) All of the above. Answer: D Explanation: Overloading allows multiple routines with the same name but different signatures. Question 10. In Delphi, which loop guarantees that the body executes at least once? A) for…do B) while…do C) repeat…until D) case…of Answer: C Explanation: The repeat…until loop evaluates the condition after executing the body. Question 11. Which visibility specifier restricts access to the declaring class and its descendants only? A) private B) protected C) strict private D) public Answer: B Explanation: protected members are accessible within the class and its subclasses. Question 12. What does the “override” directive indicate in a method declaration? A) The method replaces an inherited virtual method.
Preparation Guide
B) The method cannot be called from outside the class. C) The method is static. D) The method is abstract. Answer: A Explanation: override implements a new version of an inherited virtual (or dynamic) method. Question 13. Which keyword is used to declare a class method that can be called without an instance? A) static B) class C) virtual D) abstract Answer: B Explanation: class methods are invoked on the class type itself, not on an object instance. Question 14. How do you declare a property named Age with read access via GetAge and write access via SetAge? A) property Age: Integer read GetAge write SetAge; B) property Age: Integer read SetAge write GetAge; C) property Age: Integer read GetAge; write SetAge; D) property Age: Integer read GetAge; write SetAge; Answer: A Explanation: The read specifier names the getter, write specifier names the setter.
Preparation Guide
Explanation: TInterfacedObject implements IInterface and handles AddRef/Release internally. Question 18. Which RTL function converts a string to an integer, raising an exception on failure? A) StrToInt B) IntToStr C) TryStrToInt D) Val Answer: A Explanation: StrToInt raises EConvertError if the string cannot be parsed. Question 19. Which method of TFileStream opens a file for reading only? A) fmOpenReadWrite B) fmCreate C) fmOpenRead D) fmOpenWrite Answer: C Explanation: fmOpenRead opens an existing file for read-only access. Question 20. What is the effect of calling the Free method on a nil object reference? A) Raises an Access Violation. B) Does nothing; it is safe. C) Calls the destructor anyway. D) Sets the variable to nil automatically.
Preparation Guide
Answer: B Explanation: Free checks for nil before invoking Destroy, making it safe to call on nil. Question 21. In Delphi’s memory model, where are static arrays allocated? A) Stack B) Heap C) Global data segment D) Managed heap Answer: C Explanation: Static arrays have fixed size and are placed in the program’s global data segment. Question 22. Which statement correctly releases an interface reference without affecting other references? A) MyInterface := nil; B) MyInterface.Free; C) MyInterface.Release; D) MyInterface.Destroy; Answer: A Explanation: Setting the interface variable to nil decrements the reference count; other references remain valid. Question 23. What is ARC (Automatic Reference Counting) primarily applied to in Delphi mobile compilers? A) Objects derived from TObject B) Strings, dynamic arrays, and interfaces
Preparation Guide
A) They contain only compiled .dcu files. B) They are loaded by the application at runtime. C) They provide components that appear on the IDE palette. D) They cannot contain resource files. Answer: C Explanation: Design-time packages register components with the IDE, making them available on the component palette. Question 27. What is the purpose of the “uses” clause in the implementation section of a unit? A) To expose symbols to other units. B) To import symbols only needed for implementation. C) To define the unit’s namespace. D) To declare global variables. Answer: B Explanation: The implementation-uses clause limits visibility to the unit’s implementation, reducing compile-time dependencies. Question 28. Which exception class is the base class for all Delphi exceptions? A) EAbort B) EError C) Exception D) TObjectException Answer: C Explanation: All standard Delphi exceptions descend from the Exception class.
Preparation Guide
Question 29. In a try…except block, which clause catches all exceptions regardless of type? A) on E: Exception do … B) else … C) finally … D) on E: TObject do … Answer: A Explanation: “on E: Exception do” matches any exception derived from Exception, which includes all Delphi exceptions. Question 30. What does the Assert procedure do when the condition evaluates to False and assertions are enabled? A) Raises an EAssertionFailed exception. B) Writes a message to the console and continues. C) Calls Halt(1). D) Does nothing; it’s ignored in release builds. Answer: A Explanation: Assert raises an exception (EAssertionFailed) to signal a failed condition during debugging. Question 31. Which generic collection class provides a type-safe list with dynamic resizing? A) TArray B) TDictionary C) TList D) TObjectList Answer: C
Preparation Guide
Answer: B Explanation: TFDConnection encapsulates the connection parameters and manages the physical DB link. Question 35. Which method of TDataSet moves the cursor to the next record? A) NextRecord B) MoveNext C) Next D) SeekNext Answer: C Explanation: The Next method advances the dataset’s current record pointer. Question 36. What is the default property of TComboBox that displays the selected text? A) Items B) Text C) ItemIndex D) Value Answer: B Explanation: The Text property reflects the currently displayed string of the combo box. Question 37. Which statement correctly creates a FireDAC query that selects all rows from the “Customers” table? A) FDQuery1.SQL.Text := 'SELECT * FROM Customers'; FDQuery1.Open; B) FDQuery1.CommandText := 'SELECT * FROM Customers'; FDQuery1.Execute; C) FDQuery1.SQL.Add('SELECT * FROM Customers'); FDQuery1.Active := True;
Preparation Guide
D) FDQuery1.Query := 'SELECT * FROM Customers'; FDQuery1.Open; Answer: A Explanation: Assigning to SQL.Text and calling Open prepares and runs the SELECT statement. Question 38. Which compiler directive disables range checking for the whole unit? A) {$R+} B) {$R-} C) {$OVERFLOWCHECKS OFF} D) {$BOUNDSCHECK OFF} Answer: B Explanation: {$R-} turns off range checking; {$R+} turns it on. Question 39. What does the “strict private” visibility specifier prevent? A) Access from descendant classes. B) Access from the same unit. C) Access from any other unit, even the same one. D) Access from the implementation section. Answer: A Explanation: strict private restricts visibility to the defining class only; regular private also allows access from other classes in the same unit. Question 40. Which of the following is a correct way to declare a set of values from an enumerated type TColor = (red, green, blue)? A) var MySet: set of TColor; B) var MySet: set of (red, green, blue);
Preparation Guide
B) Input; C) GetLine; D) ConsoleRead; Answer: A Explanation: ReadLn reads a line from the console (standard input). Question 44. Which unit provides the Now function that returns the current date and time? A) System.SysUtils B) System.DateUtils C) System.TimeSpan D) System.Math Answer: A Explanation: Now is declared in SysUtils (which is part of the System namespace). Question 45. What is the result of the following expression: Length('Delphi')? A) 5 B) 6 C) 7 D) 0 Answer: B Explanation: Length returns the number of characters; “Delphi” has 6 letters. Question 46. Which of the following statements about the “finalize” section of a unit is FALSE? A) It is executed after the initialization sections of all units.
Preparation Guide
B) It is used to free resources allocated by the unit. C) It runs before the program’s main block finishes. D) It can be omitted; the compiler will generate one automatically. Answer: C Explanation: finalize runs after the program’s main block has completed, during program termination. Question 47. Which method of TComponent is called automatically when the component is dropped onto a form at design time? A) Create; B) Loaded; C) InitializeComponent; D) RegisterComponent; Answer: B Explanation: Loaded is invoked after streaming the component’s properties from the DFM file. Question 48. How do you declare a class that implements two interfaces, IFirst and ISecond? A) TMyClass = class(TInterfacedObject, IFirst, ISecond) … end; B) TMyClass = class(IFirst, ISecond) … end; C) TMyClass = class(TObject, IFirst) implements ISecond; … end; D) TMyClass = class(TInterfacedObject) implements IFirst, ISecond; … end; Answer: A Explanation: The class inherits from TInterfacedObject (or another base) and lists the interfaces after the base class.
Preparation Guide
A) Allocates memory for an AnsiString of a given length. B) Allocates a new UnicodeString. C) Allocates a block of memory for a PChar. D) Frees a previously allocated string. Answer: C Explanation: StrAlloc returns a pointer to a newly allocated block of memory for a PChar of the specified size. Question 53. Which of the following is a correct way to raise a custom exception class EMyError? A) raise EMyError.Create('Error occurred'); B) raise new EMyError('Error occurred'); C) raise Exception('EMyError: Error occurred'); D) raise EMyError('Error occurred'); Answer: A Explanation: Custom exception classes are instantiated with Create and raised with raise. Question 54. Which statement correctly frees a dynamically allocated object reference stored in variable Obj? A) Dispose(Obj); B) Obj.Free; C) Delete(Obj); D) Release(Obj); Answer: B Explanation: Calling Free on a TObject instance releases it safely (checks for nil).
Preparation Guide
Question 55. In a generic class TStack, which constraint would you use to require that T has a parameterless constructor? A) T: constructor; B) T: class, constructor; C) T: IInterface; D) T: record; Answer: B Explanation: “class, constructor” enforces that T is a class type with a parameterless constructor. Question 56. Which of the following statements about the “out” parameter modifier is TRUE? A) The caller must initialize the variable before the call. B) The callee must assign a value before exiting. C) The parameter is passed by value. D) It behaves identically to “var”. Answer: B Explanation: “out” parameters are intended for the callee to assign a value; they are not required to be initialized by the caller. Question 57. Which component can be used to display data from a TFDQuery in a grid? A) TFDGrid B) TDBGrid C) TDataGrid D) TGridView Answer: B
