C / C++ / MFC Discussion Boards

Re: Is it possible to modify the dialog style at run time?

Chris Meech26-Jul-12 6:08

26-Jul-12 6:08

The article you linked to changes the style from WS_CHILD to WS_POPUP. It also suggests that it can not happen the other way around, that is from WS_POPUP to WS_CHILD. Are you sure you're making the same style change? Smile | :)

Chris Meech
I am Canadian. [heard in a local bar]

In theory there is no difference between theory and practice. In practice there is. [Yogi Berra]

posting about Crystal Reports here is like discussing gay marriage on a catholic church’s website.[Nishant Sivakumar]

Linker Error :C1900

pix_programmer25-Jul-12 18:59

pix_programmer

25-Jul-12 18:59

Hi!
Can any one tell me how to solve this error?

C1900: Il mismatch between 'P1' version '20060201' and 'P2' version '20050411'

Re: Linker Error :C1900

Malli_S25-Jul-12 20:25

Malli_S

25-Jul-12 20:25

Which VS version you are using? Did you recently updated the VS ? If so, repairing the installation might work for you.

When I googled for more details, I found this[^].

[Delegates] [Virtual Desktop] [Tray Me !]

-Malli...!

Re: Linker Error :C1900

pix_programmer26-Jul-12 19:59

pix_programmer

26-Jul-12 19:59

Hi!
Installing the SP1 for Visual Studio 2005 fixed this error. Thank you.

Re: Linker Error :C1900

Malli_S26-Jul-12 20:15

Malli_S

26-Jul-12 20:15

[Delegates] [Virtual Desktop] [Tray Me !]

-Malli...!

Compiler job

_Flaviu25-Jul-12 9:26

_Flaviu

25-Jul-12 9:26

I have a similar question, the one that somebody ask me recently : If I have a simple class, with only one method

C++

class Foo
{
public:
    Foo();
    virtual ~Foo();

    void DoSomething();
};

what generate the compiler ? Code for constructor, destructor and method DoSomething() only ? Don't generate a default copy constructor and assigning operator, even is doesn't explicity implemented ?

modified 26-Jul-12 7:22am.

Re: Compiler job

Maximilien25-Jul-12 9:47

Maximilien

25-Jul-12 9:47

The compiler will try to create the copy constructor and the assignment constructor.
Rules for Declaring Constructors[^]

Watched code never compiles.

Re: Compiler job

_Flaviu26-Jul-12 6:22

_Flaviu

26-Jul-12 6:22

Thank you for your answer.

Re: Compiler job

CPallini25-Jul-12 22:16

CPallini

25-Jul-12 22:16

Why don't you try to actually compile such code?

For instance you may discover the missed the return value type in DoSomething declaration.

Veni, vidi, vici.

Re: Compiler job

Malli_S25-Jul-12 23:10

Malli_S

25-Jul-12 23:10

[Delegates] [Virtual Desktop] [Tray Me !]

-Malli...!

Re: Compiler job

_Flaviu26-Jul-12 1:21

_Flaviu

26-Jul-12 1:21

You are perfectly right ! Laugh | :laugh:

Is there a reason you would initialise variables like this?

MarkB77725-Jul-12 1:33

MarkB777

25-Jul-12 1:33

Hi all,

Is there any particular reason you would initialise private members of a class like this...

<br />
SomeClass::Constructor(void): privateVar1(NULL), privateVar2(true) {<br />
<br />
}<br />

As opposed to this?

<br />
SomeClass::Constructor(void) {<br />
    privateVar1 = NULL;<br />
    privateVar2 = true;<br />
}<br />

From what I understand the first instance would be useful when inheritance is involved.. Perhaps this is just a favored style?

Cheers,
Mark

Mark Brock
"We're definitely not going to make a G or a PG version of this. It's not PillowfightCraft." -- Chris Metzen

Re: Is there a reason you would initialise variables like this?

_AnsHUMAN_ 25-Jul-12 1:47

_AnsHUMAN_

25-Jul-12 1:47

Const and reference members can only be initialized in an intializer list. Moreover if we don't initialize the variables in the initializers list the compiler will have to do it for us and later on in the constructor this will be initialized again. Hence, there would be two calls for variable initialization

You talk about Being HUMAN. I have it in my name
AnsHUMAN

Re: Is there a reason you would initialise variables like this?

jschell25-Jul-12 6:40

jschell

25-Jul-12 6:40

_AnsHUMAN_ wrote:
Moreover if we don't initialize the variables in the initializers list the compiler will have to do it for us and later on in the constructor this will be initialized again.

I doubt that.

The easiest way for a compiler to provide default values is to do the following
- Request memory block for the object
- Overwrite the entire block with zeros.
- Continue the construction process.

Providing code to set the default value for each member is thus not required.
Any other initialization, beyond the default value, would occur regardless.

Re: Is there a reason you would initialise variables like this?

Philippe Mori25-Jul-12 10:37

Philippe Mori

25-Jul-12 10:37

In standard C++, member without default constructor are not initialized to 0 automatically but are random.

Philippe Mori

Re: Is there a reason you would initialise variables like this?

jschell27-Jul-12 11:38

jschell

27-Jul-12 11:38

Philippe Mori wrote:
In standard C++, member without default constructor are not initialized to 0 automatically but are random.

Wrong.

Section 4.9.5 C++ specification clearly states that class member variables have a default value if they do not have an initializer.

class Any
{
  ....
  int var1 = 2; // This is an initializer.
  int var2;  // No initializer so set to default value (zero.)
  }

Local variables (those declared in a method) have not such default value.

Re: Is there a reason you would initialise variables like this?

Philippe Mori27-Jul-12 13:08

Philippe Mori

27-Jul-12 13:08

At this time, I program mainly in C# and in that case meber are initialized to (as member of a ref class would also be initialized in C++/CLI).

As far as I can tell, you have misunderstood the standard. A static member will be initialized to 0 but not a regiular member in the general case.

I have found many link that confirm what I have said.

http://www.cplusplus.com/forum/general/17582/[^]

http://stackoverflow.com/questions/1069621/are-members-of-a-c-struct-initialized-to-0-by-default[^]

http://stackoverflow.com/questions/2614809/what-is-the-default-value-for-c-class-members[^]

http://msdn.microsoft.com/en-us/library/s0wk5dy9.aspx[^]

Philippe Mori

Re: Is there a reason you would initialise variables like this?

jschell28-Jul-12 6:13

jschell

28-Jul-12 6:13

Philippe Mori wrote:
As far as I can tell, you have misunderstood the standard.

Yep, you are correct.

Re: Is there a reason you would initialise variables like this?

w-peuker26-Jul-12 21:21

w-peuker

26-Jul-12 21:21

Some compilers initialize memory to zero. But for compatibility reasons, the C++ standard leaves (built-in type) members untouched (I don't know the latest one). Of course, if your members have default constructors, they will be called (before the constructor body) unless you place them in the initializer list.

Re: Is there a reason you would initialise variables like this?

jschell27-Jul-12 11:40

jschell

27-Jul-12 11:40

w-peuker wrote:
Some compilers initialize memory to zero. But for compatibility reasons, the C++ standard leaves (built-in type) members untouched (I don't know the latest one).

Wrong. The only compilers that leave data members non-initialized would be compilers that are not implementing the ANSI C++ specification.

Section 4.9.5 C++ specification clearly states that class member variables have a default value if they do not have an initializer.

   class Any
   {
     ....
     int var1 = 2; // This is an initializer.
     int var2;  // No initializer so set to default value (zero.)
     }
<pre>

This happens regardless of how construction occurs.

Re: Is there a reason you would initialise variables like this?

Philippe Mori27-Jul-12 13:10

Philippe Mori

27-Jul-12 13:10

See my answer above. You have misunderstood the standard. I have found many links that proove otherwise. By the way, your example is not even valid C++ code.

Philippe Mori

modified 27-Jul-12 21:04pm.

Re: Is there a reason you would initialise variables like this?

jschell28-Jul-12 6:14

jschell

28-Jul-12 6:14

Philippe Mori wrote:
See my answer above. You have misunderstood the standard.

Yes, you are correct.

Re: Is there a reason you would initialise variables like this?

Richard MacCutchan25-Jul-12 1:52

Richard MacCutchan

25-Jul-12 1:52

It's just a matter of style, although I think the first option is preferred. MSDN has this to say[^] on the matter. You may also like to check if Bjarne Stroustrup has more to offer.

One of these days I'm going to think of a really clever signature.

Re: Is there a reason you would initialise variables like this?

George L. Jackson25-Jul-12 7:07

George L. Jackson

25-Jul-12 7:07

C++ FAQ by Marshall Cline says: [10.6] Should my constructors use "initialization lists" or "assignment"?
[^].

"We make a living by what we get, we make a life by what we give." --Winston Churchill

Re: Is there a reason you would initialise variables like this?

MarkB77725-Jul-12 22:45

MarkB777

25-Jul-12 22:45

Thanks George Smile | :)

Mark Brock
"We're definitely not going to make a G or a PG version of this. It's not PillowfightCraft." -- Chris Metzen

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.