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Delphi Components
What is the default extension of file when we create user components?
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How is message handling handled in Delphi?
EditCDC
- Jul 16th, 2009
Define custom messageconst WM_MY_MESSAGE = WM_USER + 0;Define handler for message type TMyForm = class(TForm) private procedure OnMyMessage(var Msg: TMessage); message WM_MY_MESSAGE;Send or Post message PostMessage(self.Handle,WM_MY_MESSAGE,0,0)
delphiking
- Jan 9th, 2009
Through event handlers. You can also define your own messages using the WMUSER constant.
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Here are some suggested Delphi interview questions. Describe how components are loaded from a DFM file at runtime. What is the difference between TGraphicControl and TWinControl? Write a function that reverses a string. If a component has another component as a property (example: TDatasource has a TDataset component as a property), what happens if the “pointed to“ component is deleted? Where does TCustomControl fit into the VCL heirarchy? What is the purpose and significance of the TPersistent class? What are the three methods required for an implementation of IInterface? What do they do? What class in the VCL heirarchy implements IInterface?
EditCDC
- Jul 16th, 2009
TGraphicControl vs TWinControlThe TGraphicControl class provides the capability to have controls which are not windowed controls (they have no window handle). TWinControl is the base class from whic...
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How is dynamic array's memory space removed in Delphi?
EditCDC
- Jul 16th, 2009
DeclarationADynamicCharArray : ^CharArrayType;AllocationADynamicCharArray := AllocMem(NumChars * sizeof(char)); ReleaseFreeMem(ADynamicCharArray, NumChars * sizeof(char));
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What are components in Delphi?
EditCDC
- Jul 16th, 2009
Components are commonly of two kindsVisual and Non-visualEx. VisualLabelsEdit boxesA visual component is one that helps make graphical building blocks.Ex. Non-visualTQueryTThread/Timer
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What is the use of Database Form wizard in Delphi?
ronaldvijay
- Jun 15th, 2009
This wizard helps you to build a Database Form with Ttabale, TDatasource and all the TDatabaseEdit Control without you droping each component.Cheers,Vijay
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What is the use of Initialization and Finalization sections of Delphi?
raphychiramel
- Mar 20th, 2009
The initialization section is?optional. It begins with the reserved word initialization and continues until the beginning of the finalization section or, if there is no finalization section, until th...
gopalar
- Oct 24th, 2008
Every delphi unit(pas file) you can have Initialization and Finalization section which will be executed during unit load and unlond respectivelyUnit2.pasunit Unit2;interfaceusesimplementationInitialization//Do your Initialization Steps HereFinalization//Do your Finalization Steps Hereend.
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What must be done to make scroll bars appear automatically in Delphi?
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Delphi Array types
What are the types of arrays handled by Delphi?
ngoski
- Nov 16th, 2008
There are two types of arrays. 1.Static - array[indexType1, ..., indexTypen] of baseType2. Dynamic - array of baseType
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What is project file in Delphi?
mahaswetha
- Sep 8th, 2008
File with .dpr extension is the project file. It comprises all the unit names used in the application along with their path in the hard disk (and the form name if the unit is associated with a .dfm fi...
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What is the clause used with Interface section of Delphi?
mahaswetha
- Sep 8th, 2008
Interface clause is used to represent the interface scetion in delphi. The interface contains the type declarations, var declarations.
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What is TForm object in Delphi?
mahaswetha
- Sep 8th, 2008
Tform is the .dfm file associated with any delphi application. Tform acts as a parent and owner for the components placed on it. Every .dfm file has a .pas file associated with end.
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What are the code sections that get added automatically by Delphi when a form is created?
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What is the use of container?
mahaswetha
- Sep 8th, 2008
Container is used to hold the components. It's the responsibility of the container to request the visible controls placed on it to paint themselves. The container is also responsible for creating and...
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What is the use of TActiveForm object in Delphi?
riyazthandora
- Jul 24th, 2008
TActiveForm is the base class for a VCL Form exposed as an ActiveX control. TActiveForm represents a form that is created by a class factory (in Delphi) or using the Active Template Library (C++) and ...
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What is the use of GlobalMemoryStatus() function in Delphi?
riyazthandora
- Jul 24th, 2008
It is a function in Delphi to find the Total memory status.It accepts TMemoryStatus variable as var parameter.It fills the variable entity with different memory status info like Total phisical...
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What is the use of unit interface section of Delphi?
sanjoymazumdar
- Jul 22nd, 2008
Every identifier (type, routine, variable, and so on) that you declare in the Interface portion of a unit becomes visible to any other unit of the program.
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What are Delphi units?
ruvenkat
- May 30th, 2008
Unit is nothing but a text file that can be complied in a module of code.there are 2 different types of units Project Source unit and it can be saved with an extension of .DPRand Source code unit with an associated form and can be saved with an extension of .PAS
Delphi Interview Questions
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