C++ :: Correct Values Passed To The Pointers - Memory Corruption
Apr 26, 2012
My project is say that it has memory leaks. When I view it in the debugger, it shows the correct values being passed to the pointers.
Code:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
bool ConfigGetEntry( char *pcFile, char *pcNameMust, char* &pcResult ) {
char pcBuffer[ 512 ];
[Code] ....
Its saying that i have memory corrupting at..
Code:
if ( !ConfigGetEntry( pcFile, pcName, pcRet ) ) return _strdup( pcDefault );
Also is it normal to have a bad pointer then point data into it to then clear that of the bad pointer. To have valid data now in that pointer.
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Feb 28, 2014
Which is more efficient in functions? Returning values or using pointers to redefine variables passed as arguments?
I mean either using:
void ptr_Func(int *x)
{
*x = *x+1
}
or
int ptr_Func(int x)
{
return x + 1;
}
In terms of speed, memory use etc.I want to know general efficiency, I know it will obviously vary with different uses and circumstances.
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Aug 31, 2014
What is the difference between initializing pointers to a memory address using the address operator like int *pointer = &x; or initializing it to a value like int *pointer = x; .. in other words how does p and q point to the same memory address in:
const int ARRAY_LEN = 100;
int arr [ ARRAY_LEN ];
int *p = arr;
int *q = &arr[0];
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Mar 31, 2012
I wrote most of a gui using clutter, using tons of global variables.
Clutter has a function which you use to connect an event or action like a mouse click to a function, and lets you pass one user data variable to it.
I wanted to eliminate globals. So I put everything in a struc to pass to each function, and after a few hours of doing all of this, I thought I almost got it working, but it's not the case.
I have this in the main
Code:
for (int i=0; i < 8; ++i )
clutter_actor_add_action(MV_CL_GUI.Actor_Wav[i], MV_CL_GUI.Wav_Action[i]);
which causes an error attempted to read or write protected memory.
When I comment that line out, the gui at least comes up, but as soon as a mouse event launches a function, the program crashes and gives a Debug Assertion Failed...click retry.
Then it points to a line in dbgdel.cpp
Code:
/* get a pointer to memory block header */
pHead = pHdr(pUserData);
/* verify block type */
_ASSERTE(_BLOCK_TYPE_IS_VALID(pHead->nBlockUse));
Here is what my struct looks like.
Code:
struct Clutter_GUI {
string ProjectName;
ClutterActor *Actor_Enter_Source_Bar;
ClutterLayoutManager *Actor_Source_Directories_Box_Layout;
int Source_Row_Selected;
ClutterAction *Action_Track_Row_Rect[12];
[code]....
Except it has about 5 times as many variables in it. And I am accessing all of the members just using object dot member syntax.
here is an example of the functions used to connect functions to events or actions.
Code:
g_signal_connect ( MV_CL_GUI.Action_Root_Row_Rect[1], "clicked", G_CALLBACK (Root_Row_1_Clicked), &MV_CL_GUI);
The last parameter is the struct I am passing to the function.and my functions look like this.
Code:
void Root_Row_1_Clicked (Clutter_GUI_Object MV_CL_GUI) {...}
But when I launch a function not with g_signal_connect, I don't use the &,
Code:
play(MV_CL_GUI)
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Dec 15, 2012
The application that I ported from 32 bit linux to 64 bit linux is crashing due to unknown memory corruption Also some time teh address is printed in 32 bit only as below
this=0x6787e0
any reason why this is happening?
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Dec 14, 2014
I am writing a code that creates a deck of cards using a doubly linked list. One function, newDeck(), is made to create a new deck if the user wants. I don't have any problems creating the deck and it all seems to work fine, but when I run the whole program and a separate function needs to utilize the nodes in my deck, I get an error. Trying to find where there was a problem, I tried displaying the values of a card node in random parts of my code. At the end of the newDeck function, after the whole deck has been created, the card still displays correctly, yet when I return back to main immediately after newDeck has been called, I noticed that the values of my cards changed to either random values or they became null. I found this strange because in between the end of my newDeck function and at this point, there is no extra code so it doesn't seem as if there is any way the pointers could have been changed. Maybe It's because I don't have a complete understanding of pointers yet but is there any way that pointers can change values when returning from a function to main?
newDeck(head, tail, n); //this is how I call the function from main.
void newDeck(Card* head, Card* tail, Card* n) //this is my function body
{
for (int i = 0; i < 4; i++)
{
[Code]....
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Sep 28, 2014
I am going to read some codes about image processing and I need to understand functions like this one below?
BOOL Trans_Geo_Affine(CImage *pImgSrc, CImage *pImgDst, BOOL bMatrix,
BOOL bHvInversed, double fScale_xx, double fFlex_xy, double fSkew_yx,
double fRotate_yy, double fTx, double fTy, int nInterpolation, BOOL bResize, BYTE cFill)
[URL]
two parameters, CImage *pImgSrc and CImage *pImgDst. I think they are class pointers and the function is passed by reference. What should I learn to understand this function and its parameters? How should I use this function? how to use the function with two parameters CImage *pImgSrc and CImage *pImgDst.
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Feb 4, 2014
I wanted to display the correct output by using a for loop at the end of my code, but for some reason it's not working correctly.
#include <iostream>
using namespace std;
int main() {
int* ipArray[3];
for(int i = 0; i < 3; i++) {
ipArray[i] = new int [5];
[Code] .....
What I wanted to do is pretty much match my 1st out put like 0 1 2 3 4 but my 2nd output only outputs 24's and I don't know why
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Mar 11, 2014
i've been writing some code for an assignment and it is mostly about pointers and string manipulations. It runs but crashes and I think it might be from over- valuating some strings maybe not. I have written in check points to make sure each function passes through but quits at findFirstPath loop, I had kept running the program through as i added more and more code. It had stopped when I near finished I believed it to just be because I hadn't finished the functions I called.
Code:
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#define MAXSTRING 10
#define TRUE 1
[Code]....
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Jun 27, 2013
The problem is the following, I am making a wrapper object of sockets in c++, since the ones in c are somewhat ugly, and not quite OOP. I can't use boost sockets since the project I am currently working on, can only use the libraries found in ubuntu 12.04 repositories, and the ubuntu 12.04 repositories are on boost-1.46. My solution was the following, three classes, AbstractSocket, ServerSocket, and Socket. AbstractSocket is the superclass of both ServerSocket and Socket. The following is the class definition of each of these classes:
class AbstractSocket {
public:
AbstractSocket();
AbstractSocket(const int file_descriptor, const struct addrinfo* local_address,
[Code].....
My problem and question is the following, on ServerSocket::accept method I have to do a "client_socket = new Socket(abstractSocket);", and in Socket::recv_all method I do something like "buffer = new unsigned char[bytes_to_receive];". These two situations are somewhat problematic to me, because I don't wish to make the caller of the methods responsible for deleting this memory.
Therefore, is there an elegant way to retrieve heap allocated space from a function/method? Or better yet, is there an elegant way of telling the caller of the method, that the memory will have to be deleted?
I thought of placing an "unsigned char* buffer" inside Socket class, and to delete the memory allocated in the destructor and on consecutive calls to recv_all, but i don't believe this is the solution, and it doesn't solves me the problem for the "accept" method.
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Feb 9, 2015
I have this code:
tgaManager.fileWriter.put((unsigned char)min(blue*255.0f,255.0f)).put((unsigned char)min(green*255.0f, 255.0f)).put((unsigned char)min(red*255.0f, 255.0f));
that should pass the value decided by the min function to an ofstream object, filewriter, that call the put method to print chars in a tga image file. When I open the file, all I see it is a huge black screen. You may be thinking that the values of blue,green and red are all zero but it is not the case.
With this code:
if (x==50 && y==50) {
cout << "Min BGR: " << endl;
cout << min (blue*255.0f,255.0f) << ' ' << min (green*255.0f,255.0f) << ' ' << min (red*255.0f,255.0f) << ' ' << x << ' ' << y << endl;
I get: Min BGR: 9.54167 29.9188 47.8701 50 50
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Feb 23, 2014
Write a constructor that initializes a new inventory object with the values passed as arguments, but which also includes a reasonable default value for each parameter.
#include "stdafx.h"
#include <iostream.h>
#include <stdio.h>
#include <string.h>
class inventory {
[Code] ....
I am not trying to get my homewotk done, just to understand my errors. It complies without problem. But doesn't run.
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Apr 1, 2013
I have been trying to make a function that compares all the values of the array and if they are all equal will return a value to print true. The problem I am having is that regardless of what values I enter the function is always returning true. Any way to tell the program o check all the values in one command instead I put them each,
Code:
#include<stdio.h>
#include<stdlib.h>
int compare(int arrayA[], int arrayB[]);
[Code]....
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Mar 21, 2015
My code is supposed to read a five to four digit code of a resistor from a file and determine the resistor's nominal, lower and upper tolerance values. I have inputted my file's first resistor code as a string so I could run tests on it but the problem that occurs is that a get the wrong values from my switch-case statements. I have put printfs after the function call to see what the values were and they turned out wrong. If I could get my return values to be right then I could be on my way coding.
#include<stdlib.h>
#include<stdio.h>
double bandNum(char x); // function prototype that will read the resistor value for the first, second and possibly third band
double bandMult(char x); // function prototype that multiplies the resistor by some value of 10
double bandTol(char x); // function prototype that the tolerance of the resistor is multiplied by
[Code] ....
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Mar 22, 2013
I am posting this simplified piece of code that is a bit confusing for me. There are two functions that I call. One shows the expected results but the result of the other one rather puzzles me.
//#define defineVecTyp Vec3f
#define defineVecTyp float
template <typename vecTyp>
vecTyp buildLaplacianPyramid(cv::Mat inputmat) {
vecTyp lapPyr;
[Code].....
Calling the function sum1 does not change the values stored in the variables val1 and val2. The output of the program is as follows:
val1= 1 ## val2= 10 // before the call of function sum1
val1= 1 ## val2= 10 // after the call of function sum1
sumOfVals= 22
This is quite obvious and as expected and I just pasted this piece of code as an example for better clarification.
However, if I call the function buildLaplacianPyramid and apply a function for Gaussian Blurring, this also effects the cv::Mat passed to the function. The line imshow("M1, after buildLaplacianPyramid",M1); therefore shows an image that is blurred. Since I am not passing a pointer to the cv::Mat I do not understand why this should be happening. I was assuming that there would be a copy of the cv::Mat M1 to be used within the function. Therefore I was expecting the cv::Mat M1 to retain its original value. I was expecting that all changes applied to cv::Mat inputmat within the function would not have any influence on the cv::Mat M1. Just like in my other example with the sum.
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Sep 2, 2014
declare
int *p[3];
that gives an array with 3 pointers, but how 3 pointers can have a link in the memory?
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Sep 30, 2013
Pointers point to an address in memory. What if I used 3 pointers: 2 to mark the first/last nodes, and the third to mark the current node being referenced? I would wrap it in a class (to make the memory management automatic, of course), but is this practical?? maybe some pseudo code will get the juices flowing:
template<class type>
class supercondensed_list{
public:
supercondensed_list();
~supercondensed_list();
[code].....
Any things I should take into consideration? I'm not exactly the most experienced with pointers, and manually managing memory, but I think it's worth trying. If this works, then my programs should, in theory, be 100% memory efficient.
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Apr 19, 2014
I have this struct declaration to create a linked list
struct node {
string y;
node* next;
};
If I create a linked list of 3 nodes
A->B->C->NULL
A->y is "a"
B->y is "b"
C->y is "c"
Since they are consecutive in memory. How far apart are the strings in memory?
I tried doing something like
int n = &(head->next->x)-&(head->x);
The problem is that I got 6 while debugging and 2 otherwise.
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Nov 16, 2013
we are currently covering double pointers and memory allocation. Currently getScrabbleWords is not working. when I compile with commented code (Main() works fine) I get a segmentation fault.
This is the purpose of getScrabbleWords:
char **getScrabbleWords(char **allWords, char letters[]):
This function takes an array of char* values (i.e. strings) representing all the words read from wordlist.txt. Each of these words is tested by callingcanWeMakeIt as a helper function, and pointers to the words that can be made are put into an array, myWords. Note, copies of the words are not made! In order to indicate the end of myWords, we terminate with a NULL pointer. Thus, if N words can be made from letters then myWords should have length N+1.
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Nov 20, 2014
I get a memory access violation when I run the below code. void createNewImage(int width, int height); this function deletes any current image data and creates a new image with the specified width/height and allocates the needed number of pixels dynamically. The new image contains four blocks with different color, red, blue, green, and black.
Code:
#include <iostream>
#include "image.h"
image::image() {
pixels = NULL;
width = 0;
height = 0;
[Code] .....
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May 23, 2013
Suppose I wished to reallocate memory (resize) an array of pointers. Why does the following not work?(The program runs, yet yields a faulty segmentation error message. Why?):
Code: char **ptrarr = (char**) malloc(sizeof(char*))
Code: ptrarr = (char**) realloc(ptrarr, (capacity) * sizeof(char*));
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Dec 21, 2014
I need to use dynamic memory allocation and use pointers to iterate through the arrays that I have already in this program. I am lost, nothing I do works and where to use the pointers. I am just looking for a push in the right direction so I can finish this project and how I can implement pointers in my program.
#include <iostream>
#include <string>
#include <cstdlib>
#include <iomanip>
#include <stdio.h>
using namespace std;
[Code]...
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Feb 26, 2013
Having some frustrating issues trying to free memory from a dynamically allocated array of pointers to linked lists. I think the problem is in how I initialize the pointers to NULL. Is there a more elegant way to have the program recognize that the list is empty so it knows to create a head node for the linked list in the function 'add_end_stub_to_array'?
I ran the code through Valgrind and it says that memory is definitely lost from this array.
This is the structure definition.
Code: struct stub_edge {
int loc_id;
int anim_type;
int mkt;
struct stub_edge *next_node;
};
Here is the code snippet from main allocating and deallocating memory to the array.
Code:
struct stub_edge **stub_list = (struct stub_edge **)malloc( sizeof(struct stub_edge *) * 12);
for (i = 0; i < 12; i++)
{
stub_list[i] = (struct stub_edge *)malloc(sizeof(struct stub_edge));
stub_list[i] = NULL;
}
stub_list = add_end_stub_to_array(end_stubs, stub_list);
destroy_end_stub_array(stub_list);
Here the function for adding nodes to the lists by reading through a dynamically allocated 2D array. (The end_stubs array is ordered by month and each linked list represents events occuring within the month).
Code:
struct stub_edge **add_end_stub_to_array(int **end_stubs, struct stub_edge **list)
{
long int i = 0;
int mon = 0;
struct stub_edge *current_node1;
struct stub_edge *new_node1;
int break1 = 0;
while(i < num_edges && break1 == 0 && mon < 12)
[Code]...
Here is the function for freeing memory from the list.
Code:
void destroy_end_stub_array(struct stub_edge **list)
{
if(list != NULL)
{
int mon = 0;
struct stub_edge *current_node1;
struct stub_edge *new_node1;
for(mon = 0; mon < 12; mon++)
[Code]...
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Jan 27, 2015
I have a program that makes change from an amount. It works fine, but the output is the correct output looped over and over. I have tried everything, but it still doesn't work. For example, a amount of 98 should print
3 quarters
2 dimes
0 nickles
3 pennies
but instead it prints
3 quarters
2 dimes
0 nickels
3 pennies
0 quarters
2 dimes
0 nickels
3 pennies
0 quarters
2 dimes
0 nickels
3 pennies
Why it's doing this?
Code:
#include <iostream>
using namespace std;
int coinscount(int& amount, int value) {
int tracker = 0;
int amountdimes = amount;
[Code].....
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Apr 5, 2014
This function below takes a pointer as an argument. What I expect to happen is, since expr++ has higher precedence than *expr, that is, the primary expression operators have higher precedence than the unary operators, pointer arithmetic should occur where we increment to the second address pointed to by dbuf, and then we should dereference the value at that address. Given that logiv, when i print dbuf[3] it should print the value pointed to at the 4th address in dbuf. However, the value it returns is 0x0 not 0x3. Why doesn't it dereference the value 0x3?
Code: void dfill(unsigned char *dbuf)
{
dbuf = (unsigned char*)malloc(4);
memset(dbuf, 0, 4);
*dbuf = 0x0;
*dbuf++ = 0x1;
*dbuf++ = 0x2;
*dbuf++ = 0x3;
printf("dbuf val: 0x%x
", dbuf[3]);
}
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Nov 14, 2013
I must write a function that has a one dimensional double array and the number of values in the array as its arguments. Normalize the values. I must also print the maximum, minimum, average and numbers of values above the average in the array.
The equation that computes the normalized value from a value x is:
Normalized x= (x-min(array))/(max(array)-min(array))
My code does not print the correct normalized value, average and values above average.
Code:
#include <stdio.h>
int findMax( double array1[], int num_elements) // This function computes the maximum value of the array
{
int i, max=-32000;
for (i=0; i<num_elements; i++)
[Code] .....
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