|
Hello all.
I am just wondering, sometimes I see things such as:
m_ListBox.ShowWindow(TRUE);
and other times I see:
m_ListBox.ShowWindow(true);
I am just wondering if there is any difference between TRUE and true / FALSE and false or if they both mean the same thing? (ie constants with the same value)
|
|
|
|
|
the difference is that TRUE is a #define and true is a constant, very much like any integer 1, 2, 3, 23423.
TRUE happens to evaluate to 1, and the integer representation of true is 1, hence you can use them interchangably. But one should always strive to "put the round ball into the round hole, and not the square hole". 
--
They say the most horrible things, but I hear violins.
When I close my eyes, I'm at the center of the sun.
|
|
|
|
|
bool is a C++ built-in type with two possible values, true and false. Nothing else.
BOOL is something MS made up for use in Windows and MFC. They needed a boolean type that worked in C and C++, and since they did this before bool was added to C++, they couldn't just reuse bool. BOOL is defined as:
typedef int BOOL;
#define FALSE 0
#define TRUE 1 The trouble with those definitions is that the BOOL notion of "true" is not 1 but non-zero. A function that returns a BOOL may return 1 to mean "true", or some other nonzero number (I've seen it myself, can't recall the API names off-hand though).
Because of that, you should never test a BOOL variable/function against TRUE, just test as a boolean and the language rules will take care of the rest.
You should, in general, use bool for your own code, assuming it's C++. You can pass a bool to a function expecting a BOOL because the bool gets promoted automagically by the language rules to the integer 0 or 1, for false or true respectively, which satisfies the definition of BOOL.
--Mike--
Ericahist | CP SearchBar v2.0.2 | Homepage | 1ClickPicGrabber New v2.0! | RightClick-Encrypt
If my rhyme was a drug, I'd sell it by the gram.
|
|
|
|
|
afaik is BOOL an unsigned int, but thats not very important
scio me nihil scire
My OpenSource(zlib/libpng License) Engine:
http://sourceforge.net/projects/rendertech
Its incurable, its a Pentium division failure.
|
|
|
|
|
|
k
then it was something other.....
scio me nihil scire
My OpenSource(zlib/libpng License) Engine:
http://sourceforge.net/projects/rendertech
Its incurable, its a Pentium division failure.
|
|
|
|
|
Gotcha!
Thanks for the replies, that explained it perfectly!
|
|
|
|
|
Hello all.
A little preface, I'm really new at programming with Visual C++. I've just installed VS .NET on my machine and have purchased a few books.
I have finally gotten down the CFileDialog class and I can use it to select a file with ease. I am wondering if there is a similar way to select a folder/directory?
I have searched for quite some time (I usually search for at least 30-90 minutes or more before I post a message here), and cannot find anything to help me. I've found a DirPkr class, but it appears it was written for VC++ 6 and there are about 50 errors when I compile in VC .NET, and I'm not advanced enough to know what the problems are. I was wondering if there was an easy class out there for VS .NET (or a way to easily adapt CFileDialog, or maybe another class in MFC to do this?) I've searched the MSDN site too but cannot find anything. I am getting better at wording my searches though 
Thanks!
Shultas
|
|
|
|
|
There is a shell function called SHBrowseForFolder that does this. There is an article here[^] about a wrapper for it that may give you some hints.
Software Zen: delete this;
|
|
|
|
|
BINGO! THANK YOU! (yep, i'm shouting
That's exactly what I was looking for and this example there worked great. Sometimes I just sit there and enter a bunch of phrases into the search box "select folder" "pick folder" "choose folder" and I usually find what I'm looking for. This time, none of the choices that I used yielded a result.
Thanks for the quick reply. I will be able to sleep tonight.
Oh wait, it's only 8:30, that means I've got 8 more hours to play! 
|
|
|
|
|
|
Hi guys.
I want to draw in layers, so if anybody could give me a hint about that, I would really appreciate it. I want to be able to draw in multiple layers, so for instance if I am to erase a rectangle or any other more complex object, I would only discard a layer and repaint that object as altered, not having to redraw the background or anything else. It is something like in Photoshop when you draw on the layer and you bring it to the front, then you can delete the whole layer at any moment later.
I only need a general guidance, not the actual code.
Thanks.
|
|
|
|
|
Hi,
I think this is possible. Why don't you decrease the background color when erasing. Like Red when erased become light red. Then you will have a layout and user can redraw or repaint according to layout.
Thanks & Regards,
Salman
Live and Let live
|
|
|
|
|
This is not possible, cause the background drawing will be complex and I can not go pixel by pixel redrawing it so to appear as erased. There has to be a solution for this.
Thanks
.
|
|
|
|
|
Hi guys.
I want to draw in layers, so if anybody could give me a hint about that, I wopuld really appreciate it. I want to be able to draw in multiple layers, so for instance if I am to erase a rectangle or any other more complex object, I would only discard a layer and repaint that object altered, not having to redraw the background and everything else. It is something like in Photoshop when you draw on the layer and you bring it to the front, then zou can delete the whole layer at any stage later.
I only need a general guidance, not the actual code.
Thanks.
|
|
|
|
|
u would keep each layer in a separate memdc and composite them together when u draw the image
then u have controls to select the current layer etc etc
draw from back to front when u composite
"there is no spoon"
biz stuff about me
|
|
|
|
|
Hi,
I'm using ODBC to connect to a MS Access database.
Here is what I would like to do:
Load a CComboBox with one of the fields in a table from the database (no problem).
Then, when selecting items in the CComboBox, have a bunch of CEdit boxes loaded with the corresponding row in the table.
Can I use a SQL statment similar to this, as in VB6???:
CString sSQL;<br />
sSQL = "SELECT * FROM tablename WHERE fieldname = selectedcoboboxitem";
I just can't figure out how to do it.
Hope someone can help me out!
Also is it possible to compact and repair a MS Access database through the ODBC???
Thanks in advance.
|
|
|
|
|
no u cant do that in raw sql from any language
u would have to do something like:
"select fieldname1,fieldname2,fieldname3 from table where blah = blee"
then i would suggest u use a clistcontrol to display them and allow in-place editing of the reqd columns (u might need a custom clistcontrol from here to do the editing)
"there is no spoon"
biz stuff about me
|
|
|
|
|
Thanks for your reply but could you please give me an example on how to select fields in a database based on the selection of a combobox.
The SQL statment won't accept CStrings.
I would really appreciate it.
Thanks again!
|
|
|
|
|
Please disregard my previous message!
I have found out how to do it myself.
|
|
|
|
|
Lets say I have a Play() function that starts playing a media file when you press the P key on the keyboard.
My situation is as follows. I am recieving commands from an IR receiver. When you press a key on the remote control that is associated with play I want to send a "message" or event that tells my application that it should execute the Play() function.
So, my question is how can I simulate pressing the P key without physically pressing the key. I guess this would be similar to those programms like Girder and uIce that send keystroke messages to a given window.
Thanks,
Steve
|
|
|
|
|
You can simulate keypresses by sending WM_KEYDOWN and WM_KEYUP messages, if your application is a windowed app. An alternate approach would be to have both the keyboard handler and the IR receiver handler call a common Play() function.
Software Zen: delete this;
|
|
|
|
|
My application is dialog based. I just tripped across the SendInput() function which will help me do as you have suggested. I think in my circumstance your suggestion of the keyboard handler and the IR receiver handler calling a common Play() function is a good fit for how my project is setup.
Thanks for your input.
Steve
|
|
|
|
|
background info:
i currently have an MDI app (created with Visual Studio .NET 2003) that can properly create new child windows. each of these windows contains a rendered scene via OpenGL. all of my OpenGL calls are invoked from within an overloaded OnPaint() method. i enabled double-buffering so animations are smooth. i also overloaded the OnEraseBkgnd() method so the background will not be repainted when the child window is resized.
the problem:
when i make a selection from the main menu bar i noticed the menu dropshadow flickers when it occludes/overlays a portion of the child window.
my first assumption was that my scenes were too complex; the flickering exposes the slow "repaints" of the scene. as such, i made the necessary changes so that each child window only displays a blank grey background. the problem, however, persists for even this most simple of scenes.
i next looked up the online documentation regarding the CWnd::OnPaint() method. the docs state the framework calls OnPaint() only once by default. to verify this i set a breakpoint in my OnPaint() method only to discover it gets called dozens of times!
i suspect the flickering is due to the framework calling the OnPaint() over and over and over again. an artifact from the time-consuming "repaints" is this flickering of the menu dropshadows.
does anyone have any suggestions on how to ensure that OnPaint() is only called when necessary? any help would be greatly appreicated. thanks.
|
|
|
|
|
Hi,guys.I have a question to ask,anyone could help?
In VC++ 6 ,I build a SDI program,and add a dialog class used ClassWizard.
In the dialog class CPP file,I include the file of the view.
/#include "hotel_misview.h"
then complied this project ,the complier gave me the message follow:
<br />
i:\microsoft visual studio\myprojects\database\hotel_mis\hotel_misview.h(21) : error C2143: syntax error : missing ';' before '*'<br />
i:\microsoft visual studio\myprojects\database\hotel_mis\hotel_misview.h(21) : error C2501: 'CHotel_MISDoc' : missing storage-class or type specifiers<br />
i:\microsoft visual studio\myprojects\database\hotel_mis\hotel_misview.h(21) : error C2501: 'GetDocument' : missing storage-class or type specifiers<br />
could anyone tell me why?Thanks a lot.
===============
YES, I am here.
===============
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
