Visual C++ :: CDHtmlDialog - Memory Management
Feb 27, 2014
I have a MFC app that has a CDHtmlDialog embedded in it. During run time i update the HTML content from the C++ code. There's a IMAGE tag in the content and the SRC for the tag is updated multiple times in a second to show different images.
Basically i go over a WHILE loop in the C++ and call a JavaScript function to update the "src" for the "img" tag.
The issue am seeing is that, after running this code for a while the application kinda hangs and the system takes up lot's of memory.
How to solve this, as all the code that's in the browser side of app is HTML & JavaScript. I looked through the C++ code plugged all memory leaks there.
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Mar 21, 2014
I have an assignment that wants me to better understand how certain calls like malloc() and free() work. I'm supposed to have one function that allocates a pool of memory for the program to use (this is the only place where I'm allowed to use the malloc function. Anyplace else is off limits, except when allocating space for data structures.) Another function needs to be defined that allocates memory from this large pool of memory that we have already allocated. A third function needs to free a block of memory when a call from function main is made and a fourth does something else (haven't gotten that far yet.) I'm not sure if it's ok or not, but I'll attach the pdf form that describes all the requirements. If that's not ok, I'll delete it.)
Anyways, when thinking of data structures to use for this particular problem, one doesn't jump out at me as being THE data structure that would be most useful. How I would imagine using it is to store the addresses currently being used as well as the block length of those addresses (so basically, each node of the linkedlist would have a pointer that points to an allocated address and another field that told the size of the allocated block of memory.) How to communicate to the large pool of memory that a certain block of memory has been allocated and shouldn't be used until a free is made on that specific block of memory.
Attached File(s)
pa3.pdf (61.07K)
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Feb 21, 2014
I have a CDHtmlDialog app in which am trying to add a CSS media query in the HTML file as shown below, but it doesn't work.
@media (max-width:20em) {
table, thead, tbody, tfoot, th, td, tr { display:block; }
tr + tr { margin-top:1em; }
}
The same CSS works fine if i open in a browser like IE, FireFox, Chrome. But inside the CDHtmlDialog app this doesn't work.
I am using Visual Studio 2012 for development and have IE 11 installed in my machine.
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Aug 30, 2013
I am trying to use CDHtmlDialog in a MFC dialog based project.
What i want to achieve is pretty sample. Have one image, one button and one text box in the HTML page.
And then dynamically change this based on a timer. i.e., there're multiple images in the folder and it will change every seconds. Once the button is clicked, the timer stops and no more image changes. Same time when image changes the text in the text box also should change.
I know this is pretty simple, but for some reason i am not able to make the image even display in the dialog.
I am using Visual Studio 2012 in Windows 7 machine.
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Apr 9, 2014
I am using CDHtmlDialog in my MFC application to create a UI with HTML, CSS & JavaScript.
In my project there's one dialog created from CDHtmlDialog and a corresponding HTML file for that dialog.
Now during run time i want to change the contents of the HTML file.
Not just the HTML part, i want to change the CSS & JavaScript too.
So basically what am trying to do is, change the entire content of the default HTML file.
Is this possible? If yes, how can i do that?
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Feb 1, 2013
How to use library management inputs
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Oct 27, 2014
I am suppose to make a value to attach to a array and then have it stop on the last one with an error if it were to go past (done more or less).
Problem is I am suppose to use a int to hold the value of the array and then add 1 each time but my question is, if you were to add another number to increase your current array slot, what would that look like as I image that going array[0] + 1 isn't going to make it array[1].
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Mar 11, 2013
I am supposed to write a program that reads lines from files and see if the first character is an odd number, if so it will out put the remaining characters to output file, else itll seek to the beginning of the next line, this is what i came up with but its not working as it should, im not sure if its the version im using or the program I wrote, the commented part below was another algorithm I was trying to use.
#include<fstream>
#include<iostream>
using namespace std;
int main() {
char c;
int i =0;
[Code] ....
My text file was as follows:
input.txt
3Ali
4Sami
6Rashid
3Aya
output was unexpected , although some was relatively write but not as I wanted...
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Jan 27, 2014
I'm writing a Hotel magmt app. I'm having difficulty on how to implement a hotel attendant selecting/secure multiple rooms(with nos) for a Customer using combobox or listbox or something. How my interface will look like and techniques.
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Nov 1, 2013
what are the advantages of files and how do we operate on binary files
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Mar 16, 2014
I'm building a simple system management console application. I've abstracted the console "Menu" and derived from it a "WelcomeMenu" class with public inheritance.
The problem is that when instantiating a Menu* object and assigning it a new WelcomeMenu...I'm still not able to use WelcomeMenu's "ShowWelcomeMessage() with the Menu* object. Instead, I get "error: Class 'Menu' has no member function call 'ShowWelcomeMessage().' Which is true, but I thought a pointer-to-Menu object should be able to use the public methods of derived classes without casting in this case. Code follows.
// Menu and WelcomeMenu Classes
#ifndef MENU_H
#define MENU_H
#include <ctime>
#include <iostream>
#include <string>
[Code] .....
I get a compiler error when running this simple program:
#include <iostream>
#include <ctime>
#include "Utilities.h"
#include "Menu.h"
using namespace std;
[Code]....
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Mar 1, 2015
I am trying to figure out the best way to approach a part of a project I am working on for school. I need to put in a 6 digit account number that will not allow duplicates for another user. How to approach this .
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Apr 2, 2013
Create an a simple Payroll Management Application using the concept of Binary Tree. The program will allow you to add, sort, view, search record. The application have also the capability to save and retrieve data in a file.
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Feb 18, 2013
I have a JPEG in memory as a char* and a bytesize, if I save it to disk with a .jpg extension it's a perfect JPEG file. The thing is, I don't want to save it unless it's a minimum width/height. I got it into memory using a socket recv() call. What should I do ?
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Apr 21, 2013
I use Visual C++ to write a native C++ application. How to know the maximum memory it will use during its execution?
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Oct 26, 2013
I am using CByteArray as a buffer in Visual C++. I want to preallocate nSize memory for for CByteArray, so that later when I try to change the buffer, by calling SetSize, Add, Remove, etc., as long as all these operations are within nSize, CByteArray will not try to release the memory or reallocate the memory, so to eliminate the possibility of memory fragments in heap. Is that possible?
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Mar 4, 2015
I am developing a Visual C++ application. There is an object called CMyObject, as follows:
typedef CMap<UINT, UINT, void *, void*> CMyMap;
class CMyObject {
public:
CMyMap *m_pMyMap;
"Some other member variables"
}
Some instances of CMyObject contains a map, some not. Therefore, to save memory, I define a pointer m_pMyMap and create a new CMap object only if the instance contains a map.
When I test my app, with the increase of the CMyObject instance, the number of memory blocks allocated and deallocated is also increasing. There are a lot of fragments during this period. To prevent this, I try to override the new/delete operator for CMyObject and CMyMap. But still find many fragments. So I try to trace into the MFC source codes for CMap. I find CMap is just using an internal buffer to store the hash table(m_pHashTable), as follows:
m_pHashTable = new CAssoc* [nHashSize];
And for each hash entry, it uses:
P = (CPlex *)new BYTE[sizeof(CPlex) + nMax *cbElement];
To allocate the spaces.
I believe these two may be the reason of the memory fragments and want to eliminate them. However, is there a way to override the new/delete operator for codes such as:
new CAssoc* [nHashSize]
and
(CPlex *)new BYTE[sizeof(CPlex) + nMax *cbElement]
So that the spaces will be allocated from my own memory manager instead of from the default heap?
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Apr 29, 2013
I know memory leak checking can sometimes have false positives. I turned on memory leak checking by adding
Code:
#define _CRTDBG_MAP_ALLOC
#include <stdlib.h>
#include <crtdbg.h>
Then calling
Code:
_CrtDumpMemoryLeaks();
in the App's constructor.
I traced the issue back to the constructor for a variable included in the app class. The variable is a class I declare in the project.
Code:
//Class declaration
#define NUM_MT_COLORS 16
struct clrTable {
COLORREF clrCode;
CString clrName;
[Code] ....
I get a memory leak error for every instance where a CString is set. I tried moving this to the MainFrame just to see if there was something with this being in the app, and saw the same memory leak errors.
I didn't include the functions in this class that manipulate this table. I didn't put it in the document because this is a multi-doc application and this table is universal to the program.
Is this an example of a false positive in the memory leak checker, or did I do something wrong?
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Dec 20, 2012
when ending my app in the debugger, memory leaks will be shown like this:
Detected memory leaks!
Dumping objects ->
C:PROGRAM FILESVISUAL STUDIOMyProjectsleaktestleaktest.cpp(20) : {18}
normal block at 0x00780E80, 64 bytes long.
Data: < > CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD
Object dump complete.
How can I tell Visual c++ also to show me the memory leaks in a called dll?
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Oct 31, 2013
When running my code in Visual Studio, there is a particular point in the code where my program is crashing. To debug this, I am adding a break point in Debug mode just before that point, and observing what happens as I step through the code. However, to get to this break point in the code takes about a minute of running the program. So I'm wondering if there is a tool in Visual Studio to reload the state of a program's memory from a previous run, so that I can immediately get to the break point without having to wait for a minute each time?
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Mar 23, 2013
I am trying to use PCA, but it gives memory access violation error. Here is my sample code.
Code:
int main(...) {
.................
vector<float>input_array;
for(i=0;i<number_of_lines;i++) {
for(j=0;j<feature_vector_size;j++) {
input_array.push_back(read_feature[i][j]);
[code]....
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Jan 21, 2013
I am getting "driver could not be loaded due to system error 8" error while connecting to SQL Server 2005 from VC++. Its also throwing out of memory error. Basically i am developing and ISAPI dll. I use the following code to connect to DB.
CDatabase DBConnection;
if(! DBConnection.IsOpen()) {
DBConnection.OpenEx("Driver={SQL Server};Server=10.120.110.30;Database=Test;Trusted_Connection=yes;", CDatabase:penReadOnly | CDatabase::noOdbcDialog);
[Code] .....
for CDatabaseConnection, i can see 2 different method to open the connection, OpenEx and Open. Whats the difference between OpenEx and Open?
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Aug 6, 2013
I am using new operator, I don't recall what the allocator's name is. But what is the corresponding Exception (or derived classes) any try-catch block can cope with?
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Mar 17, 2013
I have CAN Dll program for my application,which was separately used.Now I have included the Drivers program into my application Program and I am having this error System Access Violation Exception:Attempted to read or write protected memory.i am attaching the Dll code and Application code which is throwing this error.
[CODE]
The CAN Dll Code
int receive_data(unsigned char *data_output, int *MsgId, XLportHandle g_xlPortHandle){
XLstatusxlStatus, xlStatus_new;
XLevent xlEvent;
unsigned intmsgsrx=RECEIVE_EVENT_SIZE;
char *local_data ="11111111";
DWORD status;
xlStatus_new = xlSetNotification(g_xlPortHandle, &h, 1);
[code]...
My Application Code which is the receiver thread for accessing the messages got onto the CAN bus.
DWORD WINAPI Rcv_Msg(LPVOID param){
int*MsgId = new int;//msg id from CAN
intRcvVal;//0 = there is data in the queue; 1 = there is no data
unsigned int uMsgId;
*MsgId = 0;
unsigned char CanData[8];
[code]...
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Mar 19, 2013
I had a quick question regarding a program I am trying to complete. I have the basics worked out, and everything seems to be done, but I am running into two issues.
1= The program keeps telling me "Run-Time Check Failure #3 - The variable 'order' is being used without being initialized."
and
2= When I reach my output screen I receive "Unhandled exception at 0x7751c41f in CISC 192 Project 3.exe: Microsoft C++ exception: std:Out_of_range at memory location 0x002eefb8.."
While the first one isn't necessarily a deal breaker the second one definitely is.
Code:
// Bookstore Project 3.cpp : Defines the entry point for the console application.
// Declarations
#include "stdafx.h"
#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <string>
#include <istream>
[Code] ....
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May 11, 2013
I'm trying out the gmp library by building a simple pi calculation program (original, I know!). On a million digits of Pi I've debugged the program and seem to have about a megabyte too much of memory at the end of the program (I start with around 250k before any allocation begins and end at around 1200).
int main(int argc, char *argv[]) {
//set a//
int digitsofpi =1000000;
mpf_set_default_prec(log2(10) *digitsofpi );
mpf_t a;
mpf_init (a);
mpf_set_ui (a,1);
[code].....
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