Re: Using pointers with an array - C / C++ / MFC Discussion Boards

Anonymous15-Sep-04 7:52

15-Sep-04 7:52

I'm trying to set up a function which sorts the 10 elements of my array utilizing pointers. It's just a learning exercise for my C++ class. Can anyone explain why the following code only makes 1 iteration and how I can get it to keep moving?

void sort(int iArr[], int size)
{
int *iPtr = iArr;
for (int i = size-1;i>0;--i)
for (int j=0; j<i; ++j)
="" if="" (*iptr=""> *iPtr+1);
{
int temp = *(iPtr);
*(iPtr) = *(iPtr+1);
*(iPtr + 1) = temp;
}
}

Re: Using pointers with an array

C^hris L^osinger15-Sep-04 8:07

C^hris L^osinger

15-Sep-04 8:07

Anonymous wrote:
for (int j=0; j if (*iPtr > *iPtr+1);

do you mean:
for (int j=0; j if (*iPtr > *(iPtr+1));
?

also, don't you need to move the pointer somewhere? looks like iPtr is always pointing at the first element of the array.

Software | Cleek

Re: Using pointers with an array

Dawners15-Sep-04 9:18

Dawners

15-Sep-04 9:18

It seems as though no matter where I put the code to increment iPtr, I still only get one iteration. Seems like this should be so simple, but no matter what I do I can't get it to work. The assignment was to take a previous assignment and write it so that the print & sort funtions are handled with pointers instead of arrays. Can you give me advice as to where in the code that I wrote I would insert the increment? Yes, I'm a newbee. I took structural C 4 years ago and I'm afraid I've lost a lot in 4 years. Confused | :confused:

Re: Using pointers with an array

C^hris L^osinger15-Sep-04 9:25

C^hris L^osinger

15-Sep-04 9:25

it's kindof hard to tell what's going on with your code, since the board reformatted it a bit.

try reposting it inside <pre>...</pre> tags, and put spaces after any < signs (like in your for loops and in the if(...). that should keep the board from doing too much damage.

Software | Cleek

Re: Using pointers with an array

Dawners15-Sep-04 9:32

Dawners

15-Sep-04 9:32

Thanks for your help. At this point my class is in 3 hours, so I'm going to just get the teacher to help me out. I think part of the problem is that I'm basing this portion of code on the original program which didn't utilize pointers, and I'm getting very confused. Your time is much appreciated. This is a great board. Take Care,
Dawn Smile | :)

Re: Using pointers with an array

David Crow15-Sep-04 9:28

David Crow

15-Sep-04 9:28

Anonymous wrote:
Can anyone explain why the following code only makes 1 iteration...

What is the value of size? If it is 2, then the outer loop would only execute one time.

There are other reasons why this routine will not produce the desired result but we'll get to those once the loop issue is resolved.

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

Re: Using pointers with an array

Dawners15-Sep-04 10:03

Dawners

15-Sep-04 10:03

When I wrote this little program below, I didn't even define the value of size, and it executes with the desired results. I get one print out of the array, and the second time the print function executes the list is sorted. When I try to employ this same logic using pointers, the sort loop only makes one iteration:

#include <iostream>
using namespace std;

void Print (int [], int);
void Sort (int [], int);

void main()

{
const int max =10;
int list [max] = {7, 4, 9, 1, 8,
3, 6, 5, 0, 2};
Print (list,max);
Sort (list, max);
Print (list, max);
}
void Print (int array [], int size)
{
for (int i=0; i<size; i++)
cout="" <<="" array="" [i]="" "="" ";
cout="" endl;
}

void="" sort="" (int="" [],="" int="" size)
{
for="" i="size-1;i">0;--i)
for (int j=0; j<i; ++j)
if="" (array="" [j]=""> array [j+1])
{
int temp = array[j];
array[j] = array[j+1];
array[j+1] = temp;
}
}

This programs works beautifully. Confused | :confused:

Re: Using pointers with an array

David Crow15-Sep-04 10:54

David Crow

15-Sep-04 10:54

Dawners wrote:
I didn't even define the value of size...

Actually you did. It had a value of 10.

When switching from array[] to pointers, keep in mind that array[j] is equivalent to *(array + j).

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

Re: Using pointers with an array

David Crow24-Sep-04 6:14

David Crow

24-Sep-04 6:14

How are you coming along with this?

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

Re: Using pointers with an array

Bob Stanneveld15-Sep-04 10:20

Bob Stanneveld

15-Sep-04 10:20

LOL

If you look really close then you would see why the loop is making all the iterations you want, but your code gets only executed once... If you used the debugger, you would've solved the problem in no-time.

I don't understand why the other people on this board have been so sloppy not to see the ; behind the 2nd for loop!!!!! Remove that and you'll have no problem...

Next time, use the debugger first.

Multiply it by infinity and take it beyond eternity and you'll still have no idea about what I'm talking about.

Re: Using pointers with an array

Tom Wright15-Sep-04 12:25

Tom Wright

15-Sep-04 12:25

Good eye;

Tom Wright
tawright915@yahoo.com

Re: Using pointers with an array

Antony M Kancidrowski16-Sep-04 2:22

Antony M Kancidrowski

16-Sep-04 2:22

Bob Stanneveld wrote:
I don't understand why the other people on this board have been so sloppy not to see the ; behind the 2nd for loop!!!!!

This is a forum display error!!! If you look closely it is a combination of 2 lines the lines should show

for (int j=0; j<i; ++j)<br />
if (*iPtr > *iPtr+1);

You need to look at the HTML source to find this out!

Ant.

I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)

Re: Using pointers with an array

Bob Stanneveld16-Sep-04 4:33

Bob Stanneveld

16-Sep-04 4:33

Oops, this is the point where I should hit myself and be ashamed of accusing people of not seeing an error that I out of a few did not see... Roll eyes | :rolleyes:

Multiply it by infinity and take it beyond eternity and you'll still have no idea about what I'm talking about.

Re: Using pointers with an array

SandeepN15-Sep-04 15:14

SandeepN

15-Sep-04 15:14

void sort(int iArr[], int size)
{
for (int i = size-1;i>0;--i)
{
int *iPtr = iArr;
for (int j=0; j < (size - 1) ; j++)
{
if ( *iPtr > *(iPtr+1) )
{
int temp = *iPtr;
*(iPtr) = *(iPtr+1);
*(iPtr + 1) = temp;
}
iPtr++;
}
}

You have forgot to increment the pointer in the inner for loop and reset the same in outer for loop

Sandeep Naik

Re: Using pointers with an array

Muhammad Azam15-Sep-04 23:41

Muhammad Azam

15-Sep-04 23:41

use the following lines of code to sort your array. basically your second for loop has syntex error and you have used wrong swaping logic.
i have rectified all those errors and hope its working fine now

here u r

void sort(int iArr[], int size)
{
	int *iPtr = iArr;
	
	for (int i = size-1;i>=0;i--)
	{
		for (int j=i-1; j>=0;j--)
		{
			if ( *(iPtr+i) < *(iPtr+j) )
			{
				int temp = *(iPtr+i);
				*(iPtr+i) = *(iPtr+j);
				*(iPtr + j) = temp;
			}
		}
	}
}

from
Azam

Creating a Bitmap On The Fly

#realJSOP15-Sep-04 6:44

#realJSOP

15-Sep-04 6:44

I'm trying to create a bitmap on the fly. Once the bitmap is created, it will be passed to a toolbar class (CodeJock's CXToolBar) to apply to a button. The following code snippet is what I have so far. It compiles but I haven't run it yet because I have some questions:

1) How close am I?

2) What am I missing?

3) Do I have to keep the bitmap around after I've passed it into the toolbar?

CString sText = "Test";

//setup the device context
CDC pDC;
pDC.CreateCompatibleDC((CDC*)::GetDC(NULL));
pDC.SetBkMode(TRANSPARENT);
pDC.SetTextColor(RGB(0,0,0));

// establish the size of the bitmap based on the length of the text
CRect bmpRect(0,0,0,0);
CSize sz = pDC.GetTextExtent(sText, sText.GetLength());
bmpRect.SetRect(0, 0, sz.cx + 4, 15);

// calculate the x pos that will allow the text to be drawn in the
// horizontal center of the bitmap
int nXPos = (int)((bmpRect.Width() - sz.cx) * 0.5);

// create the bitmap
CBitmap bmp;
bmp.CreateCompatibleBitmap(&pDC, bmpRect.Width(), bmpRect.Height());

pDC.SelectObject(&bmp);

// create the font
CFont bmpFont;
LOGFONT lf;
memset(&lf, 0, sizeof(LOGFONT));
strcpy(lf.lfFaceName,"Arial");
lf.lfQuality   = NONANTIALIASED_QUALITY; // may not want to use this
lf.lfHeight    = 8;
lf.lfWeight    = 100;
bmpFont.CreateFontIndirect(&lf);
CFont* pOldFont = pDC.SelectObject(&bmpFont);

// create a brush that uses the system button face color
CBrush bmpBrush;
bmpBrush.CreateSysColorBrush(COLOR_BTNFACE);
CBrush* pOldBrush = (CBrush*)pDC.SelectObject(&bmpBrush);

// draw the bitmap
pDC.Rectangle(&bmpRect);
pDC.TextOut(nXPos, 2, sText);

// release the resources
pDC.SelectObject(pOldBrush);
pDC.SelectObject(pOldFont);

------- sig starts

"I've heard some drivers saying, 'We're going too fast here...'. If you're not here to race, go the hell home - don't come here and grumble about going too fast. Why don't you tie a kerosene rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt

"...the staggering layers of obscenity in your statement make it a work of art on so many levels." - Jason Jystad, 10/26/2001

Re: Creating a Bitmap On The Fly

Michael Dunn15-Sep-04 9:24

Michael Dunn

15-Sep-04 9:24

From just a quick reading (I didn't run it either Wink | ;)

) it looks almost right. The only thing that looks wrong is

pDC.CreateCompatibleDC((CDC*)::GetDC(NULL));

You're casting a HDC to a CDC*, which is a bad cast since those two aren't the same thing. Use CDC::FromHandle() instead.

--Mike--
Personal stuff:: Ericahist | Homepage
Shareware stuff:: 1ClickPicGrabber | RightClick-Encrypt
CP stuff:: CP SearchBar v2.0.2 | C++ Forum FAQ
----
Pinky, are you pondering what I'm pondering?
I think so Brain, but how will we fit the hamster inside the accordion?

Transparent Check Box in Dialog

LukeV15-Sep-04 6:36

LukeV

15-Sep-04 6:36

Hi,

I'm able to make static controls transparent but I ran into some problems with check boxes. There background is black!

Here's some code:

<br />
LRESULT CDlgAntiFraudWarning::OnCtlColorDlg(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled)<br />
{<br />
	SetBkMode( (HDC)wParam, TRANSPARENT );<br />
	return (LRESULT)m_hBrushBkgr;<br />
}<br />
<br />
LRESULT CDlgAntiFraudWarning::OnCtlColorStatic(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled)<br />
{<br />
	SetBkMode( (HDC)wParam, TRANSPARENT );<br />
	return (LRESULT)m_hBrushNull;<br />
}<br />
<br />
LRESULT CDlgAntiFraudWarning::OnCtlColorBtn(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled)<br />
{<br />
	SetBkMode( (HDC)wParam, TRANSPARENT );<br />
	return 0;<br />
}<br />

What's the solution? Thanks! Smile | :)

HyperLink without mfc

Paolo Ponzano15-Sep-04 6:06

Paolo Ponzano

15-Sep-04 6:06

hello,
I just want to know how to make a string an hyperlink to an http page without using MFC, I founded here and on codeguru some example but they're for MFC code...
thanks
Paolo

Re: HyperLink without mfc

Michael Dunn15-Sep-04 9:26

Michael Dunn

15-Sep-04 9:26

On XP and 2003 there is a built-in hyperlink control. On previous OSes you can use WTL's CHyperLinkCtrl.

--Mike--
Personal stuff:: Ericahist | Homepage
Shareware stuff:: 1ClickPicGrabber | RightClick-Encrypt
CP stuff:: CP SearchBar v2.0.2 | C++ Forum FAQ
----
There is a saying in statistics that a million monkeys pounding on typewriters would eventually create a work of Shakespeare. Thanks to the Internet, we now know that this is not true.

Re: HyperLink without mfc

Paolo Ponzano15-Sep-04 20:51

Paolo Ponzano

15-Sep-04 20:51

can you please tell me how it's called and how I can apply it to a dialog box??,
I'm unable to find it into Visual Studio's Toolbox

Thanks
Paolo

Re: HyperLink without mfc

Michael Dunn16-Sep-04 9:41

Michael Dunn

16-Sep-04 9:41

See WTL for MFC Programmers, Part V[^], I have an example of using the WTL hyperlink class in that article

--Mike--
Personal stuff:: Ericahist | Homepage
Shareware stuff:: 1ClickPicGrabber | RightClick-Encrypt
CP stuff:: CP SearchBar v2.0.2 | C++ Forum FAQ
----
Pinky, are you pondering what I'm pondering?
I think so Brain, but if we shaved our heads, we'd look like weasels!
"Kosh reminded me of some of the prima-donna programmers I've worked with. Knew everything but when you asked them a question; never gave you a straight answer."
-- Michael P. Butler in the Lounge

GetAdaptersAddresses IPv6 Where the problem is ??

Alpha Siera15-Sep-04 5:30

Alpha Siera

15-Sep-04 5:30

Hi,

I am trying to get the IPv6 address. I am using following code.

IP_ADAPTER_ADDRESSES ipadd;
ULONG buflen;
DWORD err;
memset(&ipadd, 0, sizeof(ipadd));
err=GetAdaptersAddresses(AF_INET6,GAA_FLAG_SKIP_DNS_SERVER,NULL,&ipadd,&buflen);

but whenever the code is executed the application close down without any error.

I am compiling this by using WinXP SP2 SDK and using VS 6.0

Please Reply

Regards
Alpha

Re: GetAdaptersAddresses IPv6 Where the problem is ??

David Crow15-Sep-04 5:43

David Crow

15-Sep-04 5:43

How about:

IP_ADAPTER_ADDRESSES *ipadd;
ULONG buflen;
GetAdaptersAddresses(AF_INET6,GAA_FLAG_SKIP_DNS_SERVER,NULL,NULL,&buflen);
ipadd = new IP_ADAPTER_ADDRESSES[buflen];
GetAdaptersAddresses(AF_INET6,GAA_FLAG_SKIP_DNS_SERVER,NULL,ipadd,&buflen);
...
delete [] ipadd;

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

Re: GetAdaptersAddresses IPv6 Where the problem is ??

Alpha Siera15-Sep-04 18:55

Alpha Siera

15-Sep-04 18:55

Hi,

Thanx for reply It's working now. But I don't really know I am not getting the desired output. It shows all return values in box junk characters.

for example the code

CString strFinal;
IP_ADAPTER_ADDRESSES *ipadd;
ULONG buflen;

GetAdaptersAddresses(AF_INET6,GAA_FLAG_SKIP_DNS_SERVER,NULL,NULL,&buflen);
ipadd = new IP_ADAPTER_ADDRESSES[buflen];
GetAdaptersAddresses(AF_INET6,GAA_FLAG_SKIP_DNS_SERVER,NULL,ipadd,&buflen);
strFinal.Format(L"Name of Adapter %s",ipadd->AdapterName);
delete [] ipadd;

The ipadd->AdapterName returns value in junk character.

Thanks for reply
Regards
Alpha

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