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Linked List pointer printing memory leak


Linked List pointer printing memory leak

By : lovevintage
Date : November 22 2020, 10:31 AM
I wish this helpful for you There are several things wrong apart from the way you access the val field, which as has been commented should be curr->val.
Your program, when thus corrected, prints rubbish because you only print it after pointing curr to prev, and val is uninitialised.
code :
curr->val = i;
...
curr = prev;
printf ("%d\n", curr->val);
#include <stdio.h>
#include <stdlib.h>

struct node{
    int val;
    struct node *next;
};

int main(){
    int i;
    struct node *curr, *head = NULL;

    // build the list
    for (i=1; i<=5; i++) {
        curr = malloc(sizeof(struct node));
        curr->val = i;
        curr->next = head;
        head = curr;
    }

    // print the list
    curr = head;
    while (curr) {
        printf ("%d\n", curr->val);
        curr = curr->next;
    }
    return 0;


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C Linked List Memory Usage (Possible memory leak)

C Linked List Memory Usage (Possible memory leak)


By : Nilda Sendra
Date : March 29 2020, 07:55 AM
it helps some times You don't say how you are checking memory usage, but I'm going to guess that you are using ps or something similar to see how much memory the OS has given the process.
Depending on your memory allocator, calling free may or may not return the memory to the OS. So even though you are calling free, you will not see the memory footprint decrease from the OS's point of view.
How to check memory leak when dealing with linked-list naked pointer style?

How to check memory leak when dealing with linked-list naked pointer style?


By : MaX.Br4CeR.Inc
Date : March 29 2020, 07:55 AM
like below fixes the issue An alternative to a heap checker if you know which object may be a culprit is to manually instrument your code:
code :
unsigned nodes = 0;
struct node {
    ~node()
    {
        --nodes;
    }
    int value;
    node* next;
    node( int value ) : value( value ), next( NULL ) {
        ++nodes;
    }
};
int main()
{
    // etc.
    delete ls;
    std::cout << "Nodes: " << nodes << std::endl;
    return 0;
}
Fortran: How to plug memory leak from un-deallocated pointer in linked list

Fortran: How to plug memory leak from un-deallocated pointer in linked list


By : user3305189
Date : March 29 2020, 07:55 AM
Does that help The key to find the bug (after a short check with valgrind) is this piece:
code :
!      At this point I'm done with N, and N was allocated earlier by
!      either the m_NewDLL function or inside a call to m_PushFront,
!      but if I try to deallocate then it throws a runtime error that
!      N isn't allocated and cannot be deallocated.
!     deallocate(N)
       if (associated(N%Child)) then
!          N has only child node, so the child's parent pointer will now become null,
!          so that the child know's it's the new head of the list
           nullify(N%Child%Parent)
call m_Delete(L, L%Head%Parent)
==3347== 
==3347== HEAP SUMMARY:
==3347==     in use at exit: 0 bytes in 0 blocks
==3347==   total heap usage: 41 allocs, 41 frees, 12,271 bytes allocated
==3347== 
==3347== All heap blocks were freed -- no leaks are possible
==3347== 
==3347== For counts of detected and suppressed errors, rerun with: -v
==3347== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 2 from 2)
call m_Delete(L, L%Head)
Printing C linked list produces memory leak

Printing C linked list produces memory leak


By : user1895876
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further I am using Heapusage, an alternative to Valgrind. When I am printing my linked list in the main function, it produces memory leak (when the printing function is commented, it is all fine). I was trying to find out what is wrong, but the printing function is so simple, that either my heap analyzer is bugged or the problem is so simple, that I can't find it. , you have no leaks, tested with valgrind-3.14.0.GIT
code :
==13568== Memcheck, a memory error detector
==13568== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==13568== Using Valgrind-3.14.0.GIT and LibVEX; rerun with -h for copyright info
==13568== Command: ./a.out
==13568==  [2, 3]
==13568== 
==13568== HEAP SUMMARY:
==13568==     in use at exit: 0 bytes in 0 blocks
==13568==   total heap usage: 2 allocs, 2 frees, 1,040 bytes allocated
==13568== 
==13568== All heap blocks were freed -- no leaks are possible
==13568== 
==13568== For counts of detected and suppressed errors, rerun with: -v
==13568== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
Linked list with a memory leak

Linked list with a memory leak


By : Boing
Date : March 29 2020, 07:55 AM
I think the issue was by ths following , Your observations do not seem to indicate a problem:
VIRT and RES are expressed in KiB (units of 1024 bytes). Depending on how virtual memory works on your system, the numbers should always be multiples of the page size, which is most likely 4KiB. RES is the amount of resident memory, in other words the amount of RAM actually mapped for your program at a given time. If the program goes to sleep for 60 minutes at a time, the system (Linux) may determine that some of its pages are good candidates for discarding or swapping should it need to map memory for other processes. RES will diminish accordingly. Note incidentally that top is one such process that needs memory and thus can disturb your process while observing it, a computing variant of Heisenberg's Principle. When the process wakes up, whatever memory is accessed by the running thread is mapped back into memory, either from the executable file(s) if it was discarded or from the swap file, or from nowhere if the discarded page was all null bytes or an unused part of the stack. This causes RES to increase again.
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