C / C++ / MFC Discussion Boards

Re: Get List of Devices Currently Attached in a thread

David Crow13-Oct-09 2:54

David Crow

13-Oct-09 2:54

tibbasultanpur wrote:
I want whenever a new device is arrived or removed...

Do you need to respond to the WM_DEVICECHANGE message?

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

Initialize into const char**

m_mun11-Oct-09 23:15

m_mun

11-Oct-09 23:15

Hello all,
I have a function like this
void fn_VersionInfo(const char** EngineVersionInfo)
{
}
I have to initialize a string into "EnginneVersionInfo" variable of function parameter. Can any body help me.

Thanks to all

Re: Initialize into const char**

Iain Clarke, Warrior Programmer11-Oct-09 23:20

Iain Clarke, Warrior Programmer

11-Oct-09 23:20

Well, look at the parameters.

You pass it a pointer to a pointer to a bunch of chars.

In C/C++, the most basic string is a pointer to a bunch of chars, usually NULL terminated.

So, we can say that fn_VersionInfo takes a pointer to a string. So you pass a pointer to a string.

That could either be a string you create yourself, or one that function creates for you. I suspect the latter, but you'll have to read the documentation to discover that.

Where is this function from? Does it have any documentation? Can you read the source?
If you let it create a string, who is responsible for deleting it afterwards?

Answering that last question will answer your original question.
*Not* looking for the answer to my last question means you will at best get bad habits, at worst will make your software crash when two parts of it try and tidy up the same variable twice.

Iain.

ps, I appear to be dishing out lessons in paranoid programming today. Like there's any other kind...

I have now moved to Sweden for love (awwww).
If you're in Scandinavia and want an MVP on the payroll (or happy with a remote worker), or need contract work done, give me a job! http://cv.imcsoft.co.uk/[^]

Re: Initialize into const char**

m_mun11-Oct-09 23:43

m_mun

11-Oct-09 23:43

Hello Iain,
Thanks for replying.

Actually this have a documentation. I have to write the body of this function. This function exists in a DLL. I don't have to think outside code of the DLL. Sombody just call my function.

Pls reply

Re: Initialize into const char**

CPallini12-Oct-09 0:08

CPallini

12-Oct-09 0:08

Shaheen.India wrote:
void fn_VersionInfo(const char** EngineVersionInfo)
{
}

void fn_VersionInfo(const char** EngineVersionInfo)
{
  *EngineVersionInfo = "00.00.00.00";
}

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Re: Initialize into const char**

m_mun12-Oct-09 0:32

m_mun

12-Oct-09 0:32

Hello CPallini
Thanks it works fine

Re: Initialize into const char**

«_Superman_»12-Oct-09 8:58

«_Superman_»

12-Oct-09 8:58

It is a good idea to pass in a second size_t parameter which specifies the size of the memory allocated for the string. Otherwise it could lead to a buffer overrun.

And if you want to use real C++ style do this -

void fn_VersionInfo(const char*& EngineVersionInfo, size_t size)
{
   strcpy_s(EngineVersionInfo, size, "version string");
}

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

40 bit decimal to binary

Makakuin11-Oct-09 21:03

Makakuin

11-Oct-09 21:03

Hello!

Could anyone, please, forward me the right direction to do HEX->BIN->DEC conversions with 40 bit variable.

The point:

I have a CEdit type input on a dialog and a CComboBox to select data type. The user can choose to input data in HEX, DEC, BIN, formats the data length can be up to 40 bits (I use a char[5] type variable to store data in BIN). I have already made functions for getting user input from HEX and BIN (below):

<br />
void FillBuffer(void)<br />
{<br />
	CString str;<br />
	<br />
	char Bit = 0;<br />
	char Byte = 0;<br />
	char Mask = 0;<br />
	char Buf = '0';<br />
<br />
<br />
	m_CardNumber.GetWindowTextA(str);<br />
	str.MakeUpper();<br />
	<br />
	for(int i = 0;i<sizeof(Card.Data);i++)<br />
	{<br />
		Card.Data[i] = 0x00; //make sure to clear buffer..<br />
	}<br />
<br />
	int MaxLength;<br />
<br />
	switch(PrevFormat)<br />
	{<br />
		case HEX: //Read in hex store in binary<br />
			{<br />
				MaxLength = 10;<br />
<br />
				if(str.GetLength() < 10)<br />
					MaxLength = str.GetLength();<br />
<br />
				for(int i = 0;<MaxLength;i++)<br />
				{<br />
					switch(str.GetAt(i))<br />
					{<br />
					case '0':<br />
						Mask = 0;<br />
						break;<br />
					case '1':<br />
						Mask = 1;<br />
						break;<br />
					case '2':<br />
						Mask = 2;<br />
						break;<br />
					case '3':<br />
						Mask = 3;<br />
						break;<br />
					case '4':<br />
						Mask = 4;<br />
						break;<br />
					case '5':<br />
						Mask = 5;<br />
						break;<br />
					case '6':<br />
						Mask = 6;<br />
						break;<br />
					case '7':<br />
						Mask = 7;<br />
						break;<br />
					case '8':<br />
						Mask = 8;<br />
						break;<br />
					case '9':<br />
						Mask = 9;<br />
						break;<br />
					case 'A':<br />
						Mask = 10;<br />
						break;<br />
					case 'B':<br />
						Mask = 11;<br />
						break;<br />
					case 'C':<br />
						Mask = 12;<br />
						break;<br />
					case 'D':<br />
						Mask = 13;<br />
						break;<br />
					case 'E':<br />
						Mask = 14;<br />
						break;<br />
					case 'F':<br />
						Mask = 15;<br />
						break;<br />
					};<br />
					if(Bit%2 == 0 || Bit == 0)<br />
					{<br />
						Mask = Mask << 4;<br />
					}<br />
					<br />
					Card.Data[Byte] = Card.Data[Byte]|Mask;<br />
			<br />
					Bit++;<br />
<br />
					if(Bit%2 == 0)<br />
					{<br />
						Byte++;<br />
					}<br />
<br />
<br />
				}<br />
				break; //Break HEX				<br />
			}<br />
		case BIN: // read binary string, store in binary buffer<br />
			{<br />
				MaxLength = 40;<br />
<br />
				if(str.GetLength() < 40)<br />
					MaxLength = str.GetLength();<br />
<br />
				for(int i = 0;i<MaxLength;i++)<br />
				{<br />
					Buf = str.GetAt(i);<br />
					Bit++;<br />
					<br />
					if(Buf == '1')<br />
					{<br />
						Mask = 1;<br />
						Mask = Mask << ((Bit % 8 > 0) ? ( 8 - (Bit % 8) ) : 0);<br />
						Card.Data[Byte] = Card.Data[Byte] | Mask;<br />
					}<br />
<br />
					if(Bit%8 == 0)<br />
					{<br />
						Byte++;<br />
					}<br />
				}<br />
				break; //Break BIN<br />
			}<br />
		case DEC:<br />
			{<br />
<br />
				//How to handle this?<br />
<br />
				break; //Break DEC<br />
			}<br />
                default:<br />
                                break;<br />
<br />
	};<br />
	<br />
<br />
}<br />
<br />

All this works fine, but, how to handle Dec to bin in my case?

Thanks

Re: 40 bit decimal to binary

CPallini11-Oct-09 22:19

CPallini

11-Oct-09 22:19

I would use strtol (well, its longer cousin...) for it all:

BOOL fillArray(LPCSTR s, int base, unsigned char data[5])
{
  const unsigned __int64 GUARD = 1099511627776LL;
  char * pcStop;
  unsigned __int64 n =  _strtoui64(s, &pcStop, base);

  if ( n < GUARD )
  {
    unsigned char * p = (unsigned char *)(&n) + 4;
    for (int i=0; i<5; i++)
    {
      data[i] = *p;
      p--;
    }
    return TRUE;
  }
  else
    return FALSE;
}

how to check if a thread handle is available

Hari_1611-Oct-09 19:49

Hari_16

11-Oct-09 19:49

Hi All,

I want to use PosstThreadMessage() function and i want to check if the thread handle is available before that, because sometimes the thread will be created and some times the the thread might not be created ...

So if the thread is not created i want the condition to fail ...

ex:

if( handle available)
{
ThreadPtr->PosstThreadMessage(MyMessage);
}

So can you tell me how to verify this .

Thanks..
Hari

Re: how to check if a thread handle is available

Iain Clarke, Warrior Programmer11-Oct-09 20:47

Iain Clarke, Warrior Programmer

11-Oct-09 20:47

And what happens when the thread finishes between checking for calling the CheckThreadAvailability and PostThreadMessage functions?

By it's nature such a function would be useless.

I think you need to go back to your more basic design to address this issue, rather than papering over the cracks.

With multithreading, you have to imagine that you are on a multi code spiteful processor. Anything bad that could possibly happen, will.

Keep track of the thread handles. Even when a thread finishes, the handle is still valid - you need to close it with CloseHandle too. (I think MFC will do that for you, but I don't touch MFC threading with a bargepole. I use Win32 exclusively - better documented).

Iain.

Re: how to check if a thread handle is available

CPallini11-Oct-09 22:21

CPallini

11-Oct-09 22:21

You may use (with caveats suggested by the "Warrior Programmer") GetExitCodeThread function [^].
Smile | :)

convert pdf to tif file in C

billcodes11-Oct-09 18:49

billcodes

11-Oct-09 18:49

hi,
I have to convert pdf file to tif file using C .would anyone help me providing source code .regards
Bill

Re: convert pdf to tif file in C

Iain Clarke, Warrior Programmer11-Oct-09 20:55

Iain Clarke, Warrior Programmer

11-Oct-09 20:55

No-one is going to give you a few lines of code to do this.

As you don't already realise this, you have a lot of learning / work ahead of you.

You need to find / pay for a pdf library that can render a PDF into a HDC.

Capture that HDC (which could be very large) into a bitmap.

Convert that bitmap into a tiff.

What about multipages? Maybe your pdf library can "print" one page at a time?

I hope that helps you with your google search terms. I know there are articles on CP for bitmap to tiff. And for simple PDF rendering.

Iain.

Re: convert pdf to tif file in C

billcodes11-Oct-09 22:08

billcodes

11-Oct-09 22:08

you can provide me code in c# also

Re: convert pdf to tif file in C

CPallini11-Oct-09 22:24

CPallini

11-Oct-09 22:24

Do you understand "gimme codez" doesn't work here, don't you?

Anyway, you may try: "gimme codez urgentz plz plz" or "gimme codez ASAP".
Smile | :)

Re: convert pdf to tif file in C

Iain Clarke, Warrior Programmer11-Oct-09 22:45

Iain Clarke, Warrior Programmer

11-Oct-09 22:45

billcodes wrote:
you can provide me code in c# also

That's extremely kind of you. My answer before was not dependent on language.

Iain.

Re: convert pdf to tif file in C

AspDotNetDev15-Oct-09 15:30

AspDotNetDev

15-Oct-09 15:30

I can haz cheeseburger?

Visual Studio is an excellent GUIIDE.

Re: convert pdf to tif file in C

kilt13-Oct-09 2:23

kilt

13-Oct-09 2:23

> As you don't already realise this, you have a lot of learning / work ahead of you.
>You need to find / pay for a pdf library that can render a PDF into a HDC.

Is it a joke ?
You should learn Win32 api, GDI+, and COM : ~25 lines of code...

Re: convert pdf to tif file in C

Henry Minute13-Oct-09 5:23

Henry Minute

13-Oct-09 5:23

If you are going to sledge people, you might at least take the time and trouble to sledge the right person.

Henry Minute

Do not read medical books! You could die of a misprint. - Mark Twain
Girl: (staring) "Why do you need an icy cucumber?"
“I want to report a fraud. The government is lying to us all.”

I want to copy strings,but occur this....."Access to memory errors....",why?

milestanley11-Oct-09 17:32

milestanley

11-Oct-09 17:32

<br />
/*Copy strings*/<br />
#include "stdafx.h"<br />
#include <iostream><br />
using namespace std;<br />
<br />
/*Achieve via array*/<br />
void copy_array(char from[], char to[])<br />
{<br />
	int i = 0;<br />
	while(from[i] != '\0')<br />
	{<br />
		to[i] = from[i];<br />
		i++;		<br />
	}<br />
	to[i] = '\0';<br />
}<br />
<br />
/*Achieve via pointer*/<br />
void copy_pointer(char *from, char *to)<br />
{<br />
	while((*to++ = *from++) != '\0');<br />
}<br />
<br />
int _tmain(int argc, _TCHAR* argv[])<br />
{<br />
	char *from = "c plus plus";<br />
	char *to = "oooooooooooooooo";<br />
	//copy_array(from, to);<br />
	copy_pointer(from, to);//Here: Test.exe Department of 0x00411536 unhandled exception: <br />
			   //0xC0000005: Write Access Violation occurs when the <br />
			   //position of 0x00417ac8,Why?	<br />
<br />
	cout << to << endl;<br />
<br />
	return 0;<br />
}<br />

Re: I want to copy strings,but occur this....."Access to memory errors....",why?

theCPkid11-Oct-09 18:24

theCPkid

11-Oct-09 18:24

Any idea what's the problem in the following code?

int main()
{
  char* str = "Hello";
  str[0] = 'Y';
  cout<<str;
  return 0;
}

Re: I want to copy strings,but occur this....."Access to memory errors....",why?

Richard MacCutchan11-Oct-09 22:40

Richard MacCutchan

11-Oct-09 22:40

theCPkid wrote:
Any idea what's the problem in the following code?

Apart from the fact that it will print "Yello", nothing.

Re: I want to copy strings,but occur this....."Access to memory errors....",why?

theCPkid11-Oct-09 22:59

theCPkid

11-Oct-09 22:59

have you really tried it? i have the feeling that you will get write access error...

Re: I want to copy strings,but occur this....."Access to memory errors....",why?

Richard MacCutchan11-Oct-09 23:40

Richard MacCutchan

11-Oct-09 23:40

theCPkid wrote:
i have the feeling that you will get write access error...

Yes, you're right; my apologies.

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