Global variable and arguments to main function

[rpk2006]

I have few questions:

(1) I want to declare a variable which is GLOBAL for the whole project. Where it needs to be declared?

(2) I have added a C source file in my project, and I want to pass a string as an argument to the MAIN function of this C source. Can it be done?

(3) In circumstances where it is not known what will be the size of the returned output, I want to declare a variable length variable, similar to that of VB. Is it possible in VC++.

 

[PerFnurt]

1)
First ask yourself if its really neccessary.
If so, then ask yourself a second time.
If you still find globals is a must you can declare it as a static member of a class.

2) There can be only one (Highlander) main. At least one main being the entry point of your app. If youve incorporated some old code (with main and all) into a new c++ project, you could perhaps put the old code in a separate namespace and declare it in a .h as well.

oldstuff.h

namespace oldstuff
{
  int main(int argc, char*argv[]);
};

oldstuff.cpp

namespace oldstuff
{
   // the old main func etc...
};

Calling the old main:

   #include "oldstuff.h"

   ...
   
   char* argv[2] = { "Foo", "Bar" };
   oldstuff::main(2,argv);

3) Sure, but you have to declare it (which you dont need to in VB). What kind of variable are you talking about?

/Per

_{"It was a work of art, flawless, sublime. A triumph equaled only by its monumental failure."}

 

[rpk2006]

I should put it more clearly.

In my application, I have a feature to receive any clipboard text and then pass this text to a C program's Main Function as an argument. Now the problem is that Clipboard Data can be of varying size.

 

[PerFnurt]

...and of various type too. If its stored as normal text
its not a big deal though, as all you neeed is a pointer to the string.

if (OpenClipboard())
{

	HANDLE h = 0;
	
	if ((h = GetClipboardData(CF_TEXT))!=0)
	{
		LPCTSTR lptstr = (LPCTSTR) GlobalLock(h); 
		if (lptstr != NULL) 
		{ 
			// Do something with the string ...					
			// ...
			GlobalUnlock(h); 
		}
	}

	CloseClipboard();
}

/Per

_{"It was a work of art, flawless, sublime. A triumph equaled only by its monumental failure."}

 

[rpk2006]

Thanks, I did just that way to receive clipboard data, but I want to transfer this text as an argument to the Main Function of a C program.

Example:

void main(<Clipboard data>)

 

[PerFnurt]

Just pass it as you would with any other string, the main's implementation is part of your C++ project, right?

void main(<Clipboard data>)

Hmmm...normally a main looks like this:

int main(int argc, char*argv[]);

Where argc is stating how may strings are stored in the argv array.

So assuming you want to send it one single string you could probably do it like this:

char* argv[1];
argv[0] = const_cast<char*>lptstr;
main(1, argv);

The const_cast is terrible, but since the main excpects a non-const...however if the code is in your project = under your control you could fixe the main

int main(int argc, const char*argv[]);

and then you dont need the const_cast.

/Per

_{&quot;It was a work of art, flawless, sublime. A triumph equaled only by its monumental failure.&quot;}

 

[rpk2006]

But 'argc' and 'argv' receive arguments from command line, whereas I will pass the arguments at run-time, i.e., during program execution.

 

[PerFnurt]

>whereas I will pass the arguments at run-time,

Right. As is done in my previous post.

/Per

_{&quot;It was a work of art, flawless, sublime. A triumph equaled only by its monumental failure.&quot;}

 

[rpk2006]

Thanks a lot, I will try and reply.