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Hello,
Is it legal to 'delete' single elements of an array that was allocated all at once with 'new Array[Count]' ??
I want to allocate an array of stuff as in 'pArray = new Type[5];'
But I want to de-allocate each element one at a time as in:
for ( a = 0; a < Count; a ++ )
delete pArray[a];
It is giving me ASSERT failures in the C runtime, so I'm thinking that this may not be allowed.
Thanks,
Rich
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What's your reason for wanting to do so?
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Hi, thanks for your response. I was having a brain-lock.
Rich
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You're allocating and deleting different things. So no, generally you can't do this.
But why would you want to do so anyway? Is your array an array of pointers? If so, make sure you do a new on each element of the array, as well as the whole array.
Ryan "Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"
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You're absolutely right. It is not an array of pointers, so when I say "delete Array[a];" I'm telling it to delete the actual instance, rather than the pointer to that instance.
So I wonder why it did not give me a compiler error?
Thanks so much,
Rich
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Don't do that. If you need to construct/destruct individual objects, then a C-style array is the wrong thing to use.
If you could destruct individual members of an array, think what would happen when you later delete the array? The runtime will try to destruct the objects again.
--Mike--
Visual C++ MVP 
LINKS~! Ericahist | NEW!! PimpFish | CP SearchBar v3.0 | C++ Forum FAQ
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Hi Mike,
Thank you for your response. I will have to redesign that part of the program to do it in a different way.
Rich
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Troposphere wrote: for ( a = 0; a < Count; a ++ ) delete pArray[a];
You don't need to delete Individual memory...
you can simply delete all memory allocated to the array in one go :-
delete [] pArray
"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow
cheers,
Alok Gupta
VC Forum Q&A :- I/ IV
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Hi all 
I am having a problem with opening file for the second time. Below is the function that I wrote.
- cpHeader returns a portion of a string taken from the file
example: the file contains string "abcdefghi jklmn opqrstuvwxyz"
after some manipulations, cpHeader returns "n opqrstuvwxyz" (char*)
- cpTemp is supposedly taking in the rest of the string to process it further.
However, for the time being, it is only a dummy function, doing nothing
The problem occurs after I read a file once. Then, if I want to read another file (either it's the same or different), fileptr always returns NULL. And I received error message as "efghi jklmn opqrstuvwxyz" (not "File open error")  . I can't think of any possible reason why this error occur. Or, what is the relationship between the string manipulations and the fopen operation?
It would be very great if anybody could help me with this matter. Thanks!
void convertAndPost(AnsiString filename)
{
FILE *fileptr = NULL;
char *file = filename.c_str();
fileptr = fopen(file, "rt");
if(fileptr == NULL)
{
MessageBox(NULL,"File Open Error",NULL,0);
exit(0);
}
else
{
char* start = cpHeader(fileptr);
cpTemp(start, fileptr);
}
fclose(fileptr);
}
- Sharing information is the best way to advance together -
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kittymew wrote: And I received error message as "efghi jklmn opqrstuvwxyz" (not "File open error") . I can't think of any possible reason why this error occur. Or, what is the relationship between the string manipulations and the fopen operation?
This clearly means, that cpTemp is still involved in the file operations, and you have already returned from the method and close the file pointer even before the file operations have been completed, check out the code in cpTemp, are you returning the command back to convertAdnpost() before the file operations have been completed?
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I have it broken into 3 source files, here is the code:
#include "cstring"<br />
#include "hugeint.h"<br />
<br />
HugeInt::HugeInt( long val )<br />
{<br />
int i; <br />
<br />
for ( i = 0; i <= 29; i++ )<br />
integer [i] = 0;
<br />
for ( i = 29; val != 0 && i >= 0; i-- ) <br />
{<br />
integer[i] = val % 10;<br />
val /= 10;<br />
}<br />
}<br />
HugeInt::HugeInt( char *string )<br />
{<br />
int i, j;<br />
<br />
for ( i = 0; i <= 29; i++ )<br />
integer[i] = 0;<br />
<br />
for ( i = 30 - strlen( string ), j = 0; i <= 29; i++, j++ )<br />
if (isdigit( string[j] ))<br />
integer[i] = string[j] - '0';<br />
}<br />
HugeInt HugeInt::operator+( HugeInt &op2 )<br />
{<br />
HugeInt temp;<br />
int carry = 0;<br />
<br />
for ( int i = 29; i >= 0; i-- ) <br />
{<br />
temp.integer[i] = integer[i] + <br />
op2.integer[i] + carry;<br />
<br />
if ( temp.integer[i] > 9 ) {<br />
temp.integer[i] %= 10;<br />
carry = 1;<br />
}<br />
else<br />
carry = 0;<br />
}<br />
<br />
return temp;<br />
}<br />
HugeInt HugeInt::operator+( int op2 )<br />
{ return *this + HugeInt( op2 ); }<br />
<br />
HugeInt HugeInt::operator+( char *op2 )<br />
{ return *this + HugeInt( op2 ); }<br />
<br />
ofstream& operator << ( ofstream &output, HugeInt &num )<br />
{<br />
int i;<br />
<br />
for ( i = 0; ( num.integer[i] == 0 ) && ( i <= 29 ); i++ );
if ( i == 30 )<br />
output << 0;<br />
else<br />
for ( ; i <= 29; i++ )<br />
output << num.integer[i];<br />
<br />
return output;<br />
}<br />
<br />
#include <iostream><br />
<br />
using namespace std;<br />
<br />
class HugeInt {<br />
<br />
public:<br />
short integer[30];<br />
HugeInt();
HugeInt( long int );
HugeInt( const char * );
HugeInt operator+( HugeInt );
void operator=( HugeInt );
void print( ofstream& );
};<br />
<br />
#include <fstream>
#include "hugeint.h"<br />
<br />
using namespace std;<br />
<br />
int main()<br />
{<br />
HugeInt n1(7654321), n2(7891234),<br />
n3("99999999999999999999999999999"), n4("1"), n5;<br />
<br />
fstream fout;<br />
fout.open("file.txt");<br />
<br />
fout << "n1 is ";<br />
n1.print(fout);<br />
fout << endl;<br />
fout << "n2 is ";<br />
n2.print(fout);<br />
fout << endl;<br />
fout << "n3 is ";<br />
n3.print(fout);<br />
fout << endl;<br />
fout << "n4 is ";<br />
n4.print(fout);<br />
fout << endl;<br />
fout << "n5 is ";<br />
n5.print(fout);<br />
fout << endl;<br />
<br />
n5 = n1 + n2;<br />
n1.print(fout);<br />
fout << " + ";<br />
n2.print(fout);<br />
fout << " = ";<br />
n5.print(fout);<br />
fout << endl << endl;<br />
<br />
n5 = n3 + n4;<br />
n3.print(fout);<br />
fout << " + ";<br />
n4.print(fout);<br />
fout << " = ";<br />
n5.print(fout);<br />
fout << endl << endl;<br />
<br />
n5 = n1 + 9;<br />
n1.print(fout);<br />
fout << " + " << 9 << " = ";<br />
n5.print(fout);<br />
fout << endl; << endl;<br />
<br />
n5 = n2 + "10000";<br />
n2.print(fout);<br />
fout << " + " << "10000" << " = ";<br />
n5.print(fout);<br />
fout << endl << endl;<br />
<br />
fout.close();<br />
return 0;<br />
} <br />
<br />
My main error is 'HugeInt::print' : cannot convert parameter 1 from 'std::fstream' to 'std::ofsteam &'
but there may be more errors than this. Thanks for any help you could give!
-- modified at 14:41 Sunday 12th February, 2006
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HugeInt::print(..) code is missing?!
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hmmm that does make sense... I dont even have a HugeInt::print why would it give me an error pertaining to that? Only thing I have about print is void print(&ofstream);
Thanks for the reply, still need help 
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Hey all.
I'm working on a shell namespace extension that needs to provide access to files over the Internet.
My problem is that Explorer's UI freezes when the user attempts to drag files out of it. I've already implemented IAsyncOperation in my IDataObject, but that only seems to allow the drop *target* to run on a background thread.
I provide files through the CFSTR_FILEDESCRIPTOR/CFSTR_FILECONTENTS combo wrapped in IStream interfaces, and Explorer always calls IStream::Read() on the same thread as the rest of the UI, thus freezing everything. I'd love to either be able to return E_PENDING or something similar, or simply get called on a background thread.
For the record, I set SFGAO_ISSLOW for all items while in IShellFolder::GetAttributesOf(), but it doesn't help.
I'm slowly running out of ideas here. The interface is frozen solid while in IStream::Read(). It doesn't even redraw.
There's got to be a solution to this, that I'm just not seeing. I've been looking into async monikers, but all I managed to do was get my brain into a knot, since nowhere does the shell namespace documentation reference them, so I'm assuming there might be another way.
Any help/suggestion will be greatly appreciated.
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Hi guys
I want to know is there any way to fade out text in CStatic. Any idea or concept??
thanks
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If I was making a CStatic control to do this, I would handle the reflected
WM_CTLCOLORSTATIC message to use custom colours, and then create a timer
which updated the colour and invalidate the static control.
That should give you enough to get started with!
Iain
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Hi Iain
thanks a lot for reply.
well is there a way to fade out the text with dissolve effect.
thanks
۞It is on our failures that we base a new and different and better success.
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just crreating a new SDI project with VC++ wizard,
choose CFormView as the base view class,
then switch to the resource editor,
place a CListBox control on the formview,
and make sure to enlarge the formview design size so that a scrollbar can appear later,
then ,build it and run,
though the scrollbar is visible,
but i just can't let it scroll with my middle mouse wheel,
can anybody tell me what's the reason??
thanks a lot.
lostangels@163.com
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To perform mousewhel scrolling in a CFormView you have to enter the logic yourself.
You have to respond to WM_MOUSEWHELL.
Here's a snippet that worked for me:
BOOL CSomeFormView::OnMouseWheel(UINT nFlags, short zDelta, CPoint pt)
{
// test if it is visible first
if ( GetStyle() & WS_VSCROLL )
{
CPoint ptScroll = GetScrollPosition();
// determine the amount of scrolling
int nLines = -zDelta / WHEEL_DELTA;
// Scroll to new position
ScrollToPosition ( ptScroll + CPoint ( 0, nLines * 15 ) );
}
return CFormView::OnMouseWheel(nFlags, zDelta, pt);
}
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just crreating a new SDI project with VC++ wizard,
choose CFormView as the base view class,
then switch to the resource editor,
place a CListBox control on the formview,
and make sure to enlarge the formview design size so that a scrollbar can appear later,
then ,build it and run,
though the scrollbar is visible,
but i just can't let it scroll with my middle mouse wheel,
can anybody tell me what's the reason??
thanks a lot.
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Hi. I'm aware that this question probably has been posed for quite some time. But i'm looking for a solution where I need not compile the matlab code with matlab compiler, or build a dll as the targetted .m file is still under development. Anyone got a solution for this? Thanks!
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Hello Anonymous,
As far as I understand you look to use matlab dll files in your C++ code without calling on matlab itself. Mathworks does not provide such functionality for multiple reasons, including proprietary algorithm implementations and abstraction of implementation in order to upgrade it later. If you are REALLY serious about doing it though and you have a lot of time, you can hack into their dlls, say using dumpbin utilities and disassembler to find the binary implementations of the functions that you want to use. Perhaps, it would be easier to find open source math libraries. As a final note: Don't take my words as 100% correct, all I know is that I have talked to people with similar problems and they ended up writing their own C++ implementation. As the very final note you may also need to know that matlab internal implementation is in C rather than C++, and it also uses some Fortran compiled binaries (obj) of Lapack and Blas libraries. All this language diversity may become "pain in the place" when you try integrating your code with matlab's.
Nick Kisialiou
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Hi Nick,
after reading your reply I do agree with you. So I went a big round by creating a batch file with the commands to execute a matlab script file, and then use CreateProcess() to run the batch file. Troublesome, illogical, a big detour, but does seem to serve the purpose of executing matlab scripts without compiling or using DLL. Only problem now is to detect end of execution of matlab thread. =)
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ok I have made a program that simulates a petrol station (comming of cars etc..)
it is a single MFC /SDI app in witch I made 2 functions first one delets the screen and the second one draws someting on the screen. I call this functions whit a timer (every 100ms)
but there is a problem sometimes my program crashes and this is all that I get as help why it crashed
Unhandled exception at 0x7c28af6a (mfc71d.dll) in seminarska.exe: 0xC0000005: Access violation reading location 0x00000004.
So I'm sure that the problem is in this 2 functions :
becouse if I run the program whit no drawing the program never crashes:
ok here is the code for deleteing the screen:
void CseminarskaView::brisi_ekran(void)
{
CDC*tabla=GetDC();
RECT Okno;
GetClientRect(&Okno);
CBrush copic(0xffffff);
tabla->FillRect(&Okno,&copic);
}
and the code for drawing :
void CseminarskaView::risi(Bencinska postaja[])
{
//tukaj moram risati sproti
CDC* tabla=GetDC();
RECT ena;
ena.top=20;
ena.left=20;
ena.right=60;
ena.bottom=60;
int x1=0;
int x2=0;
int x3=255;
int y=25;
CString nizi;
int i ;
for (i=0;i<5;i++)
{
CString out;
out.Format("%i",i+1);
tabla->TextOut(10,y,out);
CBrush pisalo(RGB(x1,x2,x3));
tabla->FillRect(&ena,&pisalo);
ena.top=ena.top+60;
ena.bottom=ena.bottom+60;
x1=x1+60;
x2=x2+60;
x3=x3-60;
y=y+60;
//delete pisalo;
}
CString uu;
y=25;int y1=500;
for( i=0;i<5;i++)
{
for(int j=0;j
{ nizi=nizi+" I ";
}
tabla->TextOut(80,y,nizi);
y=y+60;
nizi=" ";
uu.Format("postaja %i: %f",i,postaja[i].rezervar);
tabla->TextOut(10,y1,uu);
y1=y1+20;
}
}
can someone please help me ?
I think that the problem is CBrush but I'm not sure
becouse sometimes the program finishes Ok sometimes not
///---there is no hope for you---\\\
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when access the NULL pointer ,the ERROR would appeal .
ALTF4 wrote: Unhandled exception at 0x7c28af6a (mfc71d.dll) in seminarska.exe: 0xC0000005: Access violation reading location 0x00000004.
the variable CBrush pisalo in the funtion risi() is abuse when for-loop run .
so you should define a ptr outside for-loop like this
...
CBrush* pBrush ;
...
for(..)
{
pBrush= new CBrush(...)
tabla->FillRect(..);
delete pBrush;
}
路漫漫其修远兮，吾将上下而求索。
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