Teach Yourself Borland C++ in 14 Days - portal

Creating Applications in C++Builder
Adding a Function to Your Code
In order to illustrate adding a function to an application, let’s implement hint text for the
ScratchPad program you wrote earlier. First, reopen the ScratchPad program. If you skipped
your homework assignment for Day 7, get ScratchPad from http://www.mcp.com/sams/
codecenter.html.
First, we need to prepare the way. We need to assign hint text to each of the speed buttons
and prepare the status bar to receive the hints. Do the following:
1. Be sure the ScratchPad main form is visible. Click the File Open speed button on
the main form’s speedbar.
2. Locate the Hint property in the Object Inspector and type the following for the
hint text:
New|Create a New File
3. Change the ShowHint property to true.
4. Repeat steps 2 and 3 for all buttons on the speedbar, adding appropriate hint text
for each type of button.
5. Click on the status bar component along the bottom of the main form. Change the
SimplePanel property to true. This will allow the full status bar to display a text
string through the SimpleText property.
Okay, now we have everything ready to go, so it’s time we did what you came here for. We’re
going to create our own OnHint handler and, not surprisingly, we’re going to name the
function OnHint(). Let’s take this one step at a time. First, we’ll add the function declaration
to the class declaration. Here goes:
1. Switch to the Code Editor and click on the SPMain.cpp tab.
2. Right-click on the Code Editor window and choose Swap Cpp/Hdr Files from the
speed menu. The SPMain.h tab appears next to the SPMain.cpp tab and becomes the
active code window.
3. Scroll down through the class declaration for the TScratchPad class until you locate
the private section. Add this line of code after the private keyword:
void __fastcall OnHint(TObject* Sender);
To give you perspective, the last few lines of the class declaration should now look
like this:
void __fastcall FormCreate(TObject *Sender);
private: // User declarations
void __fastcall OnHint(TObject* Sender);
public: // User declarations
virtual __fastcall TScratchPad(TComponent* Owner);
};
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