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Function returns null pointer instead of address


Function returns null pointer instead of address

By : Patrick Donnelly
Date : November 23 2020, 04:01 AM
Hope this helps With int* return_adress_from_input(int input), input is a value copy of k in the caller. They are two different variables therefore with different addresses.
input goes out of scope conceptually once the closing brace of the function is reached.
code :


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.Net C# ReadProcessMemory Pointer function returns address backwards

.Net C# ReadProcessMemory Pointer function returns address backwards


By : user3462114
Date : March 29 2020, 07:55 AM
With these it helps I'm new to posting on these forums but have come here multiple times for my programming help needs and have usually been able to find my answers fairly easily but I fear I might be either asking the wrong kind of questions or maybe it's very obvious and I just don't see it but here is my problem. , try
code :
    byte[] buffer = new byte[4];
    int bytesread;

    ReadProcessMemory(hProcess, dwAddress, buffer, 4, out bytesread);

    IntPtr P = new IntPtr (BitConverter.ToInt32(buffer, 0));
Function gets right pointer but returns NULL

Function gets right pointer but returns NULL


By : Alexandre Cainelli
Date : March 29 2020, 07:55 AM
hop of those help? The get_node_mt() function calls itself in two places. Neither of these two places return a value.
code :
struct node * get_node_mt(struct node *mt, int p, int h)
{
    if (h == -1) // end of tree reached
        return NULL;
    else if (mt->index == p)
        return mt;
    else if (mt->index > p)
        get_node_mt(mt->left,p,h-1);
    else
        get_node_mt(mt->right,p,h-1);
}
C: why does pointer address set to null in function, have a non-null address in main?

C: why does pointer address set to null in function, have a non-null address in main?


By : Nikon Makienko
Date : March 29 2020, 07:55 AM
I wish this helpful for you The thing is when you pass something to a function, a local copy of it is made. Now you are sending an address to the function. It is the content of t in CreateTree().
What is t in called function? t is a local variable to the CreateTree function. The type of t is org_tree* meaning it contains address of a org_tree variable.
code :
    org_tree* t;

    CreateTree(&t);

    void CreateTree(org_tree **t)
    {
        org_tree *temp;
        temp = malloc(sizeof(org_tree));
        (*t) = temp;
    }
    org_tree *t = CreateTree();

    org_tree * CreateTree(){
        org_tree *temp;
        temp = malloc(sizeof(org_tree));
        return temp;
    }
    void CreateTree(org_tree *t)
    {
        org_tree *temp;
        temp = malloc(sizeof(org_tree));
        t = temp;
        printf("%p\n", t->top); **here returns (nil) as expected
    }
passing pointer from one function to other returns a address but accessing it causes segmentation fault

passing pointer from one function to other returns a address but accessing it causes segmentation fault


By : Scott A. Schlangen
Date : March 29 2020, 07:55 AM
seems to work fine AS @Sami Kuhmonen pointed out in a comment, the problem is that when the method MainWindow.on_pushButton_clicked() is finished, all local variables are destroyed, including doc. This destroys all the nodes, elements... and so on inside the document, including of course the root node.
The simplest solution would be to return the document instead of just the root element.
code :
XMLDocument XMLUtilities::load(string filepath)
{
    XMLDocument doc;
    // ...
    return doc;
}
<cars>
    <car plate="000000">
        <owner ...
    </car>
    ...
</cars>
Initializing unsigned char pointer inside function returns null pointer

Initializing unsigned char pointer inside function returns null pointer


By : juuyyliit
Date : September 22 2020, 04:00 PM
wish help you to fix your issue The function deals with a copy of the original variable. Function parameters are its local variables.
You have to pass the pointer by reference in the C++ meaning or in the C meaning. For example
code :
void fillData(unsigned char * &data){
    data = new unsigned char[10];
    for (int i = 0; i < 10; i++){
        data[i] = static_cast<unsigned char>(i);
    }
    qDebug() << "Returning wiht non null data?" << (data == nullptr);
}
void fillData(unsigned char **data){
    *data = new unsigned char[10];
    for (int i = 0; i < 10; i++){
        ( *data )[i] = static_cast<unsigned char>(i);
    }
    qDebug() << "Returning wiht non null data?" << (*data == nullptr);
}
fillData( &data );
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