C / C++ / MFC

Gary R. Wheeler wrote:

like in C#? C++ doesn't have static constructors. I don't know if C+0x is going to support that or not (it might be nice if it did).

Gary R. Wheeler wrote:

With an instance constructor, you can set static members just like instance members. Each instance of a class can modify a static member.

class CodeProject
{
  static int x;
  int y;
   CodeProject()
  {
    x=0;
    y=0;
  }
};

int CodeProject::x;

Gary R. Wheeler wrote:

Stricly speaking, you don't have to initialize the value when you define it:

Gary R. Wheeler wrote:

n the CPP source file. The language designers left it up to the programmer where to place the definition, rather than arbitrarily placing it somewhere themselves. Interestingly enough, the C++ language places relatively few requirements on where in your source code you do things.

VuNic wrote:

why not they allow us to define it in the constructor?

Gary R. Wheeler wrote:

here isn't a way for the compiler to tell the difference between initialization, which you only want to do once for a static member, and a normal assignment, which you may want to do every time you construct a new instance.

Gary R. Wheeler wrote:

delete this;

VuNic wrote:

The above won't work without we initializing it again in the .cpp.

Stuart Dootson wrote:

You would need some intelligence in the linker to merge all allocations of the static item. Now, that intelligence might exist today, but it sure didn't back when Bjarne designed C++.

cmk wrote:

but i was looking for a real world use in C++.

Niklas Lindquist wrote:

In addition to the above comments, also notice that you might access a static variable of a class before you have any instances of it.

<br />
VideoInfoHeader hdr = new VideoInfoHeader();<br />
hdr.BmiHeader = new BitmapInfoHeader();<br />
hdr.BmiHeader.Compression = 0x68323634;<br />
<br />
vid_media.majorType = MediaType.Video;<br />
vid_media.subType = ExtraFunctions.MediaSubTypeH264;<br />
vid_media.formatType = FormatType.Mpeg2Video;<br />
vid_media.fixedSizeSamples = false;<br />
vid_media.temporalCompression = false;<br />
vid_media.sampleSize = 0;<br />
vid_media.formatSize = Marshal.SizeOf(hdr);<br />
vid_media.formatPtr = Marshal.AllocCoTaskMem(vid_media.formatSize);<br />
Marshal.StructureToPtr(hdr, vid_media.formatPtr, false);

Michael Schubert wrote:

http://ffmpeg.mplayerhq.hu/index.html[^] ?

Aniket Salunkhe wrote:

How can I use libavcodec?