Visual C++ :: CTabView - CView HWND Is NULL

Feb 25, 2014

I'm using the Feature Pack CTabView, and I noticed that when the view is added using AddView with the following code CView's HWND is NULL when I try and access each of the CView1,CView2, etc.

Code:
int CMyTabView::OnCreate(LPCREATESTRUCT lpCreateStruct) {
if (CTabView::OnCreate(lpCreateStruct) == -1)
return -1;
AddView (RUNTIME_CLASS (CView1), _T("Simple"),100);
AddView (RUNTIME_CLASS (CView2), _T("Pair"),101);
AddView (RUNTIME_CLASS (CView3), _T("Data"),102);
return 0;
}

I think the user has to click the view's tab before the CTabView assigns an HWND. Is there a way to force CTabview to give each CView an HWND when the view is added?

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Visual C++ :: How To Create Edit Box In CView

Dec 16, 2013

I'm trying to create an edit box in a CView.So far, this is how far I've gotten:

With this code

Code:
// .h
CEdit m_MyEditField;
// .c
m_MyEditField.Create(WS_CHILD | WS_VISIBLE,CRect(40,40,500,Y+55),this,0x1552);
m_MyEditField.SetWindowText("this is my CEdit field");

As you can see, the edit box doesn't look like the ones in a dialog, which is what I'm trying to accomplish.

Is there possibly some other class I should be using for the edit box?Or another setting for .Create?

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Visual C++ :: SDI CView Covered With Bitmap Resource?

Feb 10, 2013

I have an SDI / CView app (VS 2010). All works well until I minimize the app using the minimize button or drag it partially off of the screen. In the former instance, any attempt to restore the app results in an appcrash with a tight freeze up of the machine. In the later instance the same happens immediately.

In building the app, I scoured the web for code to accomplish the loading and display of the bitmap. After some experimentation I settled on overriding the OnPaint. Below is the code. Note that m_Map is a CBitmap member and IDB_BITMAP1 is a loaded bitmap resource.

Code:

void CMyDragViewView::OnPaint()
{
// CPaintDC dc(this); // device context for painting
// TODO: Add your message handler code here
// Do not call CView::OnPaint() for painting messages
// http://msgroups.net/microsoft.public.vc.mfc/loading-bitmaps-into-main-window/563285
int x = m_Map.LoadBitmap(IDB_BITMAP1);
TRACE1(" x = %d
", x);
CPaintDC* dc = new CPaintDC(this);

[code]....

I suspect that the problem is OnPaint trying to repaint the bitmap which requires reloading it, but I don't know how to work around this.

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Visual C++ :: How To Get Pointer To CDialogBar From CView Class

Nov 22, 2013

My program (Test) is a basic MFC AppWizard (exe) created project. I have followed the steps in the link below to create a docked dialog box (myDialog) using VC++. [URL]...

The dialog box works, however, I have 2 issues that I am trying to resolve.

1) I have added a button to the Dialog box, however, when I run the application they start as disabled (note: the Disabled option on the Button Properties is unchecked). If I add function myDialog::OnButton to the myDialog class, the button remains disabled, however, if I add the function CTestView::OnButton to the View class, the button becomes active and works. How can I make the button work from the myDialog class?

2) I would like to be able to change an Edit box in the same dialog box when I click the button. How can I access the pointer to the myDialog from the View class?

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Visual C++ :: Passing A Variable From CView To CDocument?

Dec 12, 2012

I am attaching a sample project. Basically what this project does is that I initialize a variable map<CString, bool*> m_mapTest in CView::OnInitialUpdate and then pass the variable to CDocument class. On the other hand, within the function OnSaveDocument defined in CDocument I check m_mapTest. To my surprise, the CString part of m_mapTest is correct but the bool* part of m_mapTest is wrong(I pass an array of bool in CView::OnInitialUpdate).

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Visual C++ :: Frozen Grid In CView Of SDI Splitter

Sep 14, 2013

I have been working with both Chris Mander's MFC grid and the Ultimate Grid.

See for details:

The Ultimate Grid Beginner's Guide By The Ultimate Toolbox, 25 Aug 2007 : [URL] ....

MFC Grid control 2.27 By Chris Maunder, 6 May 2010 : [URL] ....

Both of these grid controls work nicely in a SDI CView windows. But when I create a split window using CSplitterWnd and the following code in an attempt to create a split window with a CListView and and a CView using this code:

Code:
// in CMainFrame.h
// Attributes
public:
CSplitterWnd m_wndSplitter;
//..
// in CMainFrame.cpp
//..
BOOL CMainFrame::OnCreateClient(LPCREATESTRUCT lpcs, CCreateContext* pContext)

[Code] .....

The grid in the CView window appears but is frozen in both instances. I suspect there is some notification necessary to for the grid to send and receive messages from the split CView window, but I cannot figure out how to implement this notification.

Unfortunately, even a demo application would be too large to append, but for anyone that is interested, the split method is encapsulated in the code I've presented here and the implementation of both grid controls is well explained in the links provided.

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Visual C++ :: CArchive Load Gives Null Lines

Aug 1, 2013

I am trying to reuse some code from my Visual C++ 2005. I am using CArchive to ReadString the first line of a file into another string. However, I am seeing squares where there should be spaces when I view it in the debugger.

Here's the code:

if( cfSAP.GetStatus(csRegExtractFileRemote, cfsStatus)) {
if( !cfSAP.Open( csRegExtractFileRemote, CFile::modeRead, &ef ) ) {
cout<<"FAILED
"<<endl;
ef.ReportError();

[Code] ....

I am not able to read the lines due to this bug ,

This is normal text file contains two lines of information like this

0234568374C186-M-233545 SHAFT MATNUMBER1
0234564565C153-C-349578 BRACKET MATNUMBER2

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Visual C++ :: Token Going Null On Second Iteration Of Loop

Jan 23, 2013

Code:
while(!pile.eof()){
pile.getline(inputbuff,199,'
');
count++;

[Code] ....

the loop iterates the first time through qualifying for (count % 2 != 0) because count is at 1 so it stores the characters after the comma into tok and does it successfully according to my debugger.then the while itterates again because it doesn't qualify for the next if. this time it does qualify for count % 2 == 0 but my tok pointer is now null , how can that be? does it go null when the while loop itterates for the second time? that shouldn't be because my integer count doesn't reset?

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C++ :: Null Terminator Same As Null And Through False Value?

Feb 18, 2014

I am looking at one of the functions of an exercise:

void escape(char * s, char * t) {
int i, j;
i = j = 0;
while ( t[i] ) {
/* Translate the special character, if we have one */
switch( t[i] ) {

[code]...

Notice the while loop evaluates the current value in t to true or false. When we hit the null terminator, does that get evaluated as 0 and hence evaluates as a falsy value so the while loop exits?

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C# :: Session Is Null But Not Null?

Mar 31, 2015

When you login to my site my loginservice which is done by ajax and json make a session called context.Session["Name"]. With BreakPoints it shows that everything is good and the variables are in place. However when I use Session["Name"] it comes out as null.

I will add my code at the bottem not

using System;
using System.Collections.Generic;
using System.Linq;

[Code].....

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C :: Getting Null Pointers In Most Of Functions

Oct 15, 2014

For some reason I keep getting null pointers in most of my functions, and in my convertTime function the numbers are way higher than they should be.

Code:

//Utils.H header file----------------------------------------------

//This function takes the radius of a circle and returns the diameter, the circumference and the area.
int circleStatistics(double radius, double *diameter, double *circumference, double *area);

//This function takes a number of days and returns how many years, weeks and remaining days that is.
int convertTime(int days, int *y, int *w, int *d);

//This function takes a length of time and calculates the dilation of that time at a percentage of the speed of light.
int lorentzTimeDilation(double normalTime, double percentC, double *dilatedTime);

[Code] ....

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C++ :: Pointing To NULL And 0 The Same Thing?

Apr 13, 2014

Is:

char *endp = NULL;

the same thing as:

char *endp = 0;

?

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C++ :: Using STRTOK With Null Fields?

Jul 23, 2013

I am beginner in C++ programming. And i was try use STRTOK code with NULL fields, but in ARRAY fields NULL values is skiped. For example:

input text in Memo2:

AnsiString PAT02[100][20];
for (int IndexVRadku02 = 0; IndexVRadku02 < Memo2->Lines->Count ; IndexVRadku02++) {
AnsiString PNF02 = Memo2->Lines->Strings[IndexVRadku02];
char * PN02;

[Code] ....

Result:

Array 00 01 02 03 04 05
00 0000 TEXT1 TEXT2
01 0002 TEXT3 TEXT4 TEXT5
02 0003 TEXT6

But i need this result:

Array 00 01 02 03 04 05
00 0000 TEXT1 TEXT2
01 0002 TEXT3 TEXT4 TEXT5
02 0003 TEXT6

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C++ :: Point Of NULL In CString

Jul 9, 2014

I dont see any point of NULL in cstring. The code given below just outputs same as it would have done with NULL. My understanding is if size of char array is less than length of char array then null must be manually added?

#include <iostream>
using namespace std;
int main(){
char chr[0];
cin>>chr;//or if you use cin.getline;
cout<<chr<<endl;
return 0;
}

Enter something: hellowwwww
hellowwwww
Segmentation fault (core dumped)

why? for NULL char or something else?

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C++ :: Pointer As Parameter Is Null?

Apr 9, 2014

In my raytracer-project I have the following function:

bool hitObjects(Ray &ray, std::vector<Object *> &objects, Vector3& normal, Material *mat) {
double tmin = K_HUGE_VALUE;
double t;

[Code]....

When I try to run this, I only get the message "Material pointer is null". So, somehow the pointer is null after the hitObjects-function is called, even though it isn't inside that function.

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C/C++ :: MySQL - Resultset Is Always Null

Jul 30, 2014

The resultset is always null and the connection is alive. The VS2013 debugger says that mysqlcppconn.dll has no debugging symbols. Tested the query on a mysql console and it worked fine, it returned 1.

CDatabase::CDatabase(CSettings* settings) {
settings = settings;
try {
Connection* con = get_driver_instance()->connect("", "", "");
con->setSchema("hyperbot");
cout << "Connected." << endl << endl;

[Code] .....

I also get these strange warnings on compile:

1>c:program files (x86)mysqlmysql connector c++ 1.1.3includecppconnsqlstring.h(38):
warning C4251: 'sql::SQLString::realStr' : class 'std::basic_string<char,std::char_traits<char>,std::allocator<char>>'
needs to have dll-interface to be used by clients of class 'sql::SQLString'

[Code] ......

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C/C++ :: Strtok And Null Checking?

Mar 1, 2015

I'm playing around with parts of code and am coming across some errors. Most of my concern is related to strtok(). I've used it before but with a char* named token. I used a while loop to continuously check whether token was equal to NULL. In the following code, however, there aren't any checks. I was wondering if that is why this code prints (null) while running. Also, I would like to know if it is possible to read input like this code attempts to do - assigning tokens to each variable one after the other.

The format of the input:

Zucchini, Squash, pound
Yellow, Squash, pound
Tomatoes, Ugly Ripe, each
#include <stdio.h>
#include <stdlib.h>

[code]....

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C/C++ :: Initializing Pointer To NULL?

May 17, 2014

So I'm writing a small program for class, and for some reason I keep getting an error when trying to initialize head to NULL. Even threw in the namespace just to see, nothin'.

#ifndef NUMBERLIST_H
#define NUMBERLIST_H
using namespace std;

[Code].....

There's my header file. Not sure what I'm doing wrong with the constructor.

EDIT: Got it to work with nullptr, but still curious why that isn't working

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C# :: Linq To SQL With Null Value In WHERE Clause

Apr 13, 2015

I am trying to query fields in a where clause using LINQ to SQL and for some reason I cannot figure out why it doesn't work:

var qryGetMonsterID = (from students in dbContext.tblStudentPersonals
where (students.givenname.Equals(fn)) && (students.familyname.Equals(ln)) && (students.middlename.Equals(mn)) && (students.email.Equals(e))
select students);

The returned SQL Syntax is:

SELECT [t0].[monsterid], [t0].[givenname], [t0].[middlename], [t0].[familyname], [t0].[homeaddress], [t0].[city], [t0].[state], [t0].[postal], [t0].[primaryphone], [t0].[secondaryphone], [t0].[email], [t0].[username], [t0].[lastmodified], [t0].[modifiedby]
FROM [dbo].[tblStudentPersonal] AS [t0]
WHERE ([t0].[givenname] = @p0) AND ([t0].[familyname] = @p1) AND ([t0].[middlename] = @p2) AND ([t0].[email] = @p3)

Not sure but the values for middle name could be null - because not everyone has a middle name and the same is true for e-mail.

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C# :: Need To Replace Null Value By 0 To Calculate

Jun 28, 2014

I have a datagridview (dgv) that is bound to database:

QtyOnHand QtyOnHold QtySold QtyAvailable
10 2 1 null
12 null null null
null null null null
7 5 null null
25 null 5 null

I want to iterate through the datagridview and calculate the last column with this formula:

QtyAvailable = QtyOnHand - QtyOnHold - QtySold

so the datagridview should become:

QtyOnHand QtyOnHold QtySold QtyAvailable
10 2 1 7
12 null null 12
null null null null
7 5 null 2
25 null 5 20

I use this code:

foreach (DataGridViewRow row in dgv.Rows){
if (string.IsNullOrEmpty(row.Cells["QtyOnHand"].Value.ToString())){
row.Cells["QtyAvailable"].Value =
Convert.ToInt32(row.Cells["QtyOnHand"].Value) -
Convert.ToInt32(row.Cells["QtyOnHold"].Value) -
Convert.ToInt32(row.Cells["QtySold"].Value) -
Convert.ToInt32(row.Cells["QtyAvailable"].Value);
}
}

The problem is when any of the value on the right side of the equation is null, the whole equation is invalid. I need to replace the null values by 0 on the fly so that it can be calculated. Note that I do not want to actually replace the null values in the second and third columns of the table, just replace it in the equation whenever it applies to make the calculation work.

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C++ :: Create Null Pointer After Using Delete

Aug 7, 2014

In jumping into C++ it says something like this: It's not necessary but when you delete a pointer it's a good idea to reset it as a null pointer. That if your code try's to dereference the pointer after being freed, your program will crash. This happens to a lot of experienced programmers.

This could corrupt users data. delete p_int;
p_int = NULL;

1. If you can deference a pointer after the memory is freed, why can't you just delete the pointer?

2. If you can do 1, how do you delete the pointer using code?

3. Every thing I've read says that free memory is handed out in a sequenced order. I don't believe that is true at all. I may be wrong. Why can't you put the data in any number of places if it will fit. Isn't the compiler smart enough to know where bytes (bits)and pieces are stored?

4. If you storing anything in free memory must use a pointer to it?

5. Can a pointer or something similar be used with stack memory?

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C :: Simple Program / Null Terminator

Aug 1, 2013

my program is printing out a random symbol afterwards , when trying to copy a sequence of chars into a new buffer.

Code:

#include <stdio.h>#include <stdlib.h>
int tokenCopy(char* dest, const char* src, int destSize);
int main() {
char buff[3];
int n = tokenCopy(buff, "This is a string", 3);
printf("%d '%s'
", n, buff);

[code]....

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C# :: Getting Instance Object Is Null Compile

Dec 2, 2011

Code:

public class ColorGenetics
{
public static hk1Class jw;
public static linkedClass link;
}

[code]...

Code builds fine but compiler says I tried to use bject link w/o providing an instance. Class linkedClass has an instance of Class hk1Class set to var jw1.I had linkedClass useing the same var jw for the object instance. I changed it to jw1 thinking that would clear it up and it didn't.

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C++ :: Null Statement - Prevent Optimization

Dec 7, 2014

Recently I was looking into embedded programing of AVR microcontrollers.

At this site [URL] ....

I have encounter some code that implements delay

asm volatile ("nop");

From what I understand it is assembler code that creates delay - one processor clock long.

For C/C++ language it should be like ; or {} = null statement.

Now my question is how to implement this C/C++ code and prevent my compiler (WinAVR: AVR-GCC) to delete this command during optimization (-Os or -O2). Or is it simply better to use the assembler function.

I know I can use for-loop

volatile uint8_t foo
for(foo=0; foo<2; ++foo){}

but for that I have to create a variable = wasting 1 byte of RAM; correct?

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C++ :: Pointer Pointing To Null Still Executing

Dec 9, 2013

in the below program for both class pointers pointing to null. Class contains normal function executing but class contains virtual function getting segmentation fault.

#include <cstdio>
using namespace std;
class A
{

[Code].....

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C++ :: Null Root Binary Tree

May 19, 2013

I got problem in binary tree code. below is my code. When i select pre, post or inorder, the .exe is not responding.. Since in my binary tree theres no roots yet.. who do i solve it? It need condition or what?

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