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How to change and delete a variable in stack?


By : Jun WAKO
Date : September 16 2020, 08:00 AM
should help you out Since your collection of data is actually a linked-list which is being treated as a stack by only operating on the top (head) node, you can simply provide the code and number to identify a unique car in the list and delete that node from your list. Since both code and number members are held as type char *, you can use strcmp to compare the values. To locate and delete an individual node from the list you can use:
code :
void del_car (const char *code, const char *number)
{
    Informations **ppn = &top,      /* pointer to pointer to top node */
                  *pn = top;        /* pointer to top node */

    while (pn) {                    /* iterate over each car */
        /* compare with code and number to delete */
        if (strcmp(pn->code, code) == 0 && strcmp(pn->number, number) == 0) {
            *ppn = pn->next;        /* set node at current address to next */
            delete pn;              /* delete current node */
            return;
        }
        ppn = &pn->next;            /* advances address of current to next */
        pn = pn->next;              /* advance current to next */
    }

    fputs ("car not found.\n", stderr);     /* warn if no match found */
}


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Calling delete on variable allocated on the stack


By : Darwin Ling
Date : March 29 2020, 07:55 AM
it should still fix some issue No, it is not safe to call delete on a stack-allocated variable. You should only call delete on things created by new.
For each malloc or calloc, there should be exactly one free. For each new there should be exactly one delete. For each new[] there should be exactly one delete[]. For each stack allocation, there should be no explicit freeing or deletion. The destructor is called automatically, where applicable.

change local stack variable value


By : user2967611
Date : March 29 2020, 07:55 AM
I wish did fix the issue. The short answer is: It depends.
Per default local value types are stored on the stack but due to optimization they will often be stored only in registers as needed. Reference types are stored on the heap, with a reference to the instance on the stack (or in a register).
code :
[MethodImpl(MethodImplOptions.NoInlining)] // avoid inlining of short method
public static void Method(int x) {
    Console.WriteLine("The answer is {0}", x + x);
}
0:000> !clrstack -a
OS Thread Id: 0x1abc (0)
Child SP IP       Call Site
0035f290 003600e0 TestBench2010.Program.Method(Int32)*** WARNING: Unable to verify checksum for C:\workspaces\TestBench2010\TestBench2010\bin\Release\TestBench2010.exe
 [C:\workspaces\TestBench2010\TestBench2010\Program.cs @ 17]
    PARAMETERS:
        x (<CLR reg>) = 0x00000002

0035f294 003600a2 TestBench2010.Program.Main(System.String[])    [C:\workspaces\TestBench2010\TestBench2010\Program.cs @ 24]
    PARAMETERS:
        args = <no data>

0035f4c0 636221bb [GCFrame: 0035f4c0] 
0:000> !u 001c37f0     
Normal JIT generated code
TestBench2010.Program.Method(Int32)
Begin 003600e0, size 32

C:\workspaces\TestBench2010\TestBench2010\Program.cs @ 17:
003600e0 55              push    ebp
003600e1 8bec            mov     ebp,esp
003600e3 56              push    esi
003600e4 8bf1            mov     esi,ecx
*** WARNING: Unable to verify checksum for    C:\windows\assembly\NativeImages_v4.0.30319_32\mscorlib\658bbc023e2f4f4e802be9483e988373\mscorlib.ni.dll
003600e6 b9302be004      mov     ecx,offset mscorlib_ni+0x322b30 (04e02b30) (MT: System.Int32)
003600eb e8301fe5ff      call    001b2020 (JitHelp: CORINFO_HELP_NEWSFAST)
003600f0 8bd0            mov     edx,eax
003600f2 03f6            add     esi,esi    <==== This is x + x
003600f4 897204          mov     dword ptr [edx+4],esi
003600f7 8bf2            mov     esi,edx
003600f9 e882709d04      call    mscorlib_ni+0x257180 (04d37180)(System.Console.get_Out(), mdToken: 060008cd)
003600fe 56              push    esi
003600ff 8bc8            mov     ecx,eax
00360101 8b1534204c03    mov     edx,dword ptr ds:[34C2034h] ("The answer is {0}")
00360107 8b01            mov     eax,dword ptr [ecx]
00360109 8b403c          mov     eax,dword ptr [eax+3Ch]
0036010c ff5018          call    dword ptr [eax+18h]

C:\workspaces\TestBench2010\TestBench2010\Program.cs @ 18:
0036010f 5e              pop     esi
00360110 5d              pop     ebp
00360111 c3              ret
0:000> r ecx=15

what is the process when variable change to field,stack change to heap?


By : DasDatGuy
Date : March 29 2020, 07:55 AM
will be helpful for those in need Java objects are never stored on the stack. Always the heap. But often, there are references to those objects on the stack. In your example, those references are copied from the stack to the heap.

Why doesn't C++ give compiler error when you call delete on a non-pointer stack allocated variable?


By : oekici
Date : March 29 2020, 07:55 AM
I wish did fix the issue.
Finally accidentally I looked at the declaration of the variable being deleted and found it wasn't a pointer type at all.

How does this function change the value of a variable declared on the stack?


By : yana
Date : March 29 2020, 07:55 AM
hop of those help? Short answer is because pickPhysicalDevices explicitly allows vkEnumeratePhysicalDevices modify deviceCount variable by providing its pointer.
C++ offers multiple ways of letting a function modify a value inside another function's context - by passing a pointer or by passing a reference.
code :
void by_ref(uint32_t& ref) {
    ref = 123; // No asterisk
}
void by_ptr(uint32_t* ptr) {
    *ptr = 456; // Note the asterisk
}
int main() {
    uint32_t a, b;
    by_ref(a);
    by_ptr(&b);
    cout << a << " " << b << endl;
}
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