C :: Malloc Memory Freed When Function Exits?
May 16, 2014does memory reserved by malloc() get freed when the function it is called in finishes?
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C++ :: Valgrind Malloc Error - Pointer Being Freed Was Not Allocated
Oct 26, 2014==39800== Invalid free() / delete / delete[] / realloc()
==39800== at 0x4D9D: free (vg_replace_malloc.c:477)
==39800== by 0x10000C471: Tokenizer::~Tokenizer() (in ./a.out)
==39800== by 0x10000C424: Tokenizer::~Tokenizer() (in ./a.out)
==39800== by 0x100001B8B: main (in ./a.out)
==39800== Address 0x10002a778 is 8 bytes inside a block of size 7,208 alloc'd
[Code] ....
C++ :: Is Memory Freed Automatically In WxWidgets
May 7, 2013When using wxWidgets, i am tempted to deallocate memory using delete in the destructor, but my program crashes on closing. I try to do something like this:
class mainwnd:public wxFrame{
public:
mainwnd():wxFrame(NULL,wxID_ANY,wxT("test")){
menubar=new wxMenuBar;
[Code] .....
tell me why? and is it done automatically?
C :: Malloc Memory Allocation?
Oct 17, 2014Code:
int *p, ar[100];
p = (int *)malloc(sizeof ar);
.. *p is a pointer variable, but what means another * here --> (int *)?
C++ :: Web Server Malloc Memory Error
Dec 1, 2014I am writing a very basic database in C++ and I am accessing the data from a web browser. I am using the opensource Mongoose web server code....
I have an issue...
The way the DB works is this: on starting, the DB loads a json file of all of the data into it. I have a class called DatabaseLoader that does this - it is the class that gets rewritten depending on the data structure of the json.
This is passed to vectors (vector<Node*> and vector<Edge*>) as references from Graph object.
Once the DatabaseLoader has finished it can be destroyed and any memory allocated objects it created (except the ones in those two vectors).
From then on, the Graph object is in charge of all of the elements in the database that are stored in the two vectors. When the user browses to htpp://127.0.0.1:8000 they see the json representing each object in the vectors.
All good so far....
However, when I repeatedly hit refresh in my browser (and call me insane...) at quite a fast speed I get this error:
Code:
main(29855,0x7fff76763310) malloc: *** error for object 0x7f98b2829408: incorrect checksum for freed object - object was probably modified after being freed.
*** set a breakpoint in malloc_error_break to debug
[1] 29855 abort ./main testing.json
It seems to me this would be if I tried to "delete" and object twice, or if one of my objects was overwriting memory somewhere. However I am not recreating anything, I am just looping over the vectors and printing out the content. When I refresh slowly, I dont see this happen - i did it quite a lot of times, but when I do it fast I think it is happening.
So is there any possibility of me hitting the c++ web server to quickly and it is trying to process the data twice, causing some sort of memory error - i.e do I need to implement threading or something??
I can paste code, but there is quite a lot now....
C :: Malloc Is Used To Allocate Free Memory To A Pointer
Nov 5, 2014There is a part in the lesson that explains how malloc is used to allocate free memory to a pointer and gives us 2 examples:
Code:
float *ptr = malloc( sizeof(*ptr) ); and Code: float *ptr;
ptr = malloc( sizeof(*ptr) );
From my logic in the first case we allocate the memory to *ptr and in the second to ptr.
It's a bit confusing, am I missing something?
C :: Malloc - Verifying Amount Of Memory Allocated
Sep 7, 2013How can I view the number of bytes that have been allocated by using the malloc function?I tried:
mem = (float*)malloc(num*sizeof(float));
printf("The amount of memory allocated using malloc is %d.", mem);
Note: The variable "num" in my program is equal to 7.But every time I run the program, this value changes.
C :: Free Not Working After Malloc Was Used To Allocate Memory
Jun 13, 2014Consider this program:
Code:
// sb_string class v1.04
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct sb_string {
[Code] ....
And here is the output I got:
Code:
[harshvardhan@hari-rudra] ~/Desktop% gcc49 -o test test.c
[harshvardhan@hari-rudra] ~/Desktop% ./test
-before Value of len = 1
(in_function)-before Value of len = 1
(in_function)-after Value of len = 1
-after Value of len = 1 I was trying to make a little easier to work with string. Once the memory is allocated by malloc via sb_init() function, the sb_massacre function wasn't working to deallocate the memory. I had used multiple versions of gcc and clang but the result is same.
C++ :: KLU Library - How To Use Operator New Instead Of Malloc To Allocate Memory
May 11, 2012I have a question about the KLU library for LU factorization of sparse matrices. The KLU library accepts a pointer to a memory allocator function, by default it is malloc(). Then it uses this pointer to allocate the memory required.
I want to extend the library and I now have object of classes. I want to use the operator new instead of malloc to allocate the memory. In the same time I want the new operator to call the constructors of the objects. Is there a way to do it?
C :: How To Use Malloc Or Calloc To Create Array In Dynamic Memory
Mar 10, 2014What is wrong with my function why does it spit out huge numbers? And how do i use malloc or calloc to create an array in dynamic memory, and return a pointer to this array
Code:
#include <stdio.h>#include <stdlib.h>
int fibonacci(int n)
{
int i;
long int fib[40];
fib[0]=0;
fib[1]=1;
for(i=2;i<n;i++){
fib[i] = fib[i-1] + fib[i-2];
[Code]....
C++ :: Using Malloc / Free Multiple Times Leaves Less Memory?
Apr 17, 2014My application calls malloc in multiple subroutines, finally releasing all using free. This is done using my zalloc library (see my other post: [URL] .....
Somehow, when the applications tries to detect the available ammount of memory at the end of the test (allocating, freeing, testing), the freemem function gives me about 4-6MB less memory than at the start of the test? (out of 21MB available on the device at the start).
All memory is allocated and freed using the malloc/free routines within the library, with the exception of the SDL functions, which are registered externally on allocation and release.
C++ :: Malloc Virtual Memory - Handling Page Movements?
Jul 23, 2012When does malloc() return null ? I want to allocate a big virtual memory which can not possibly fit on RAM, so most of it will be stored on disk. I am going to access the data sequentially so at any one time the data I am working on will fit in RAM. So I am hoping the OS will move the required pages in and out of disk. I can achieve this behavior manually by allocating the required blocks on RAM but this is rather tedious. Say I have an array a[100][10000000000]. At any one time I am working only on a[i-1][], a[i][], a[i+1][] which can fit in RAM but not the whole array. So how do I allocate the array so that I can work on it using for loops for(i=0;i<100;i++) without handling the page movements myself?
View 2 Replies View RelatedC :: Call Only One Time Malloc At The Start Of Program - Memory Size Is Growing
Jan 26, 2013I have a program which call only one time malloc at the start of the program. When running, I see with 'process-explorer.exe' that memory is growing in little steps. Is this normal? why?
Using Windows 7
C :: Keep Track Of Size Of Blocks Of Memory That A Pointer Points To - Malloc Is Stuck On 8
Jan 8, 2014I'm trying to keep track of the size of blocks of memory that a pointer points to. No matter what I do, this code below always outputs the integer 8.
If I change 1000 to 5, I still get 8. If I change it to 0, I get 8... If I change it to -1, I get 8. If I change int *a to double *a, I get 8. If I take away the & symbol, I get 8. If I use *& instead, I get 8.
Why? I want it to output 1000. If I change that to 500, I want it to output 500.
int *a;
a = malloc(1000 * sizeof(int));
int j = sizeof(&a);
printf("%d", j);
I want to build my skills where I can allocate, inspect and change memory sizes.
C :: How To Get Address Returned By Malloc Function
Dec 6, 2013So, I'm in the midst of implementing my own malloc() and free() functions, but I'm having a hard time with the syntax of getting the address that malloc returns. Whenever I check the address, it's 0 Here's the code:
Code:
char *word = malloc(10);
int address = *word;
printf("%d",address);
The reason I want the address is so that I could store it in a data structure for further usage when I'm dealing with different cases for the free() function. Or is there another way to do this?
C :: Program Exits For No Reason?
Apr 29, 2014Code:
#include <stdio.h>
#include <stdlib.h>
void f(char letter,char *str) {
int i=0;
char CAPletter = 'A' + letter - 'a';
[Code] .....
OUTPUT:
//substrings starting with 'letter'
name
niros
NIce
Everything works but program quits and don't stay in console.
C :: Program Exits With Return Code Three
Aug 24, 2013Code:
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <SDL/SDL.h>
[Code]....
I don't know why since I've assigned a value like that to a variable of that same type before. Unless I had garbage data somewhere and didn't realize it.
C/C++ :: Do While Loop Not Working - Exits After Input
Feb 6, 2014My code:
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
int factorial(int n);
int main() {
int n,num;
do {
[Code] ....
My while loop is not working... it exits after 1 input...
Visual C++ :: How To Determine If A Buffer Is Freed Or Not
Dec 9, 2014I use new to allocate a buffer, as follows:
BYTE *p;
p = new BYTE[20];
...
delete p;
After p is deleted, if I do NOT assign NULL to p, is there a way to determine whether it has already been freed?
C :: Memory Overlap And Memcpy Function
Jul 21, 2013Code:
#include<stdio.h>
#include<string.h>
int main(void) {
char str[20] = "HELLOSIR";
memcpy( str + 2 , str + 1 , 4 );
puts( str );
return 0;
}
If I have understood well the above code can be a typical example that decribes a memory overlap. Some of data to the destination (str + 2 ) will be copied before its copy.
Code: void *memcpy( void * restrict s1, const void * restrict s2, size_t n );
According to the above example I think there is no quarantee even the restrict to the pointer that we won't have overlap.It is legal to use the same pointer and not other in order to have access on the data.So for this the behaviour is not undefined right?
But how memcpy works? I mean I am taking
Code: HEELLOIR as output rather than
Code: HEEEEEIR So the behaviour due to overlap is undefined?
The const on const void * restrict s2 denotes that data can't change from s2 itself?
C :: Function That Allows To Allocate Memory To Variable
Nov 8, 2013I am trying to make a function that allows me to allocate memory to a "mem" variable and setting each of its chunk's status to FREE. FREE is defined as 0. Below is my code of the function.
Code:
int allocate(mem *mm, int num_chunks, int chunk_size) {
int i;
mem *temp;
if((mm = (mem *) malloc((num_chunks + 1) * chunk_size)) == NULL){
perror("Failed to Malloc
[code]...
mem; If my function works the way it should, it should print out five 0 because that is how I set them in the function, but this is not the case. I've looked at my function for 2 hours, but I could not figure out any logical error. Now, I think my problem lies with my limited knowledge of pointer arithmetic. On the other hand, when I insert 1000 as the second argument into my function, it gives seg faults, which is not the case for smaller values like 5, 10, 15, etc.
C :: Cycling Through Memory To Print String With And Without Function
Feb 10, 2014Anyways, I have a problem where I'm trying to cycle through memory via pointers to print a string. Here is my code:
Code:
#include <stdio.h>
int main(void){
char word[]="hello there";
[Code]....
This seems to effectively portray what I want
How do I print a string using the same method for(;*pointer!='/0';pointer++) without a function?
C++ :: Allocate Memory In A Function And Call From Main
Aug 30, 2013So my assignment is to create a program that calls for a function in main that dynamically allocates an array[3] and then have pointers with multiple levels of indirection and pass them by reference so they are not lost after the function. Here is my code:
#include <iostream>
#include <array>
#include <iomanip>
#include <string>
[Code]....
Next part is to ask user for two non-negative numbers and then get the length of those numbers and create an array. for the size of each number they input. Then to separate those numbers and add the cross-sums.
C++ :: Segmentation Fault - Memory Error When Looping Over Function?
Mar 24, 2014It is been several days that I am stucked with the segmentation error and I do not know anymore what to do I try to do a loop over my function but it is working only for my first iteration. Here the code:
#include <iostream>
#include <cstdio>
#include <cstdlib>
[Code].....
I would like to iterate over solvep (since h is changing at each iteration..I usually add other fct but now I try to debug why the loop is not working.).The first iteration is working fine but not the other iterations.
C++ :: Virtual Function Table Pointer Misplaced In Object Memory
Jul 29, 2014I have found that when I dump a C++ object from memory to a file - it seems that there is a misplacement of the last Virtual-Function-Table pointer - in that appears at the beginning. The result is that the gdump information based on this object dump (using green hills) is incorrect. I copied the contents of the gdump information below. The executable is compiled in linux.
Basically MEIO::CameraStatus contains an item that relates to its parent class (line 188). Then it has 18 items that are all Diagnostics::EventsCounter items. Now for each Diagnostics::EventsCounter item there is a Virtual-Function-Table Info Pointer as its last item. All is fine and good except that the last item of MEIO::CameraStatus which is _selfReset is missing its last item of 4 bytes (which is the Virtual-Function-Table Info Pointer ). On the other hand - right before the first Diagnostics::EventsCounter item ("_vidErrors") - there is an extra 4 bytes which happens to be the Virtual-Function-Table Info Pointer. As I said the gdump information file does not see this.
Why the object memory "moves" the last Virtual-Function-Table Info Pointer to the beginning (right before _vidErrors) and is there a way to "fix" this?
///////////////////////////////////////////////////////////////////////////
"MEIO::CameraStatus" val:0x000002f0 ind208,-1) Struct-Begin Info
188: "" offset 0, Parent-Class Private Info C++ Struct ref = 114
189: "_vidErrors" offset 160, Member Info C++ Struct ref = 128
190: "_vdiErrors" offset 480, Member Info C++ Struct ref = 128
[Code] .....
C :: SegFault With Malloc
Nov 2, 2013I wrote a program to detect if a graph is tree or not. Initially it was using static memory. Later I changed it to use memory dynamically using malloc().My problem is that, my program it works great for case when graph is not tree but fails if it is.
Code:
#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
int main()
}
[code]....