Dynamic memory leak?

benzensulfonic (21)
Hello all, this is more of a conceptual question as I have not yet encountered any errors due to the shortness of my runtime right now. I have an array of pointers that point to a data structure and I have initialized it with 30 spots. Then I filled every spot with a value.

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struct example
{
    int x
    int y
} member, **pointer;

pointer = new member *[30];

//////////////////////////////////////////////////
// Here is where my question lies:
for (int i=0; i<30; i++)
{
    pointer[i] = new member;
    pointer[i]->x = 1;
    pointer[i]->y = 1;
}


I will repeat the process above (under the row of forward slashes) many times throughout my program's execution changing the value every time, and my question is: if I continue to do this without using "delete[]" until my program terminates, will I run out of memory? Any insight would be great because I would rather not progress with my code until after I know this will not leak. Thanks!

-George

BTW, I got my inspiration for this idea from another thread if it helps:
http://www.gidforums.com/t-12539.html
kbw (9488)
Yes.
benzensulfonic (21)
Well, that's good to know. Thanks. So, I will have to use "delete[]" after every time I redefine the values inside the data structure?
firedraco (6243)
I would do it right before you reassign them, yes.
benzensulfonic (21)
So, something like this?

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struct example
{
    int x
    int y
} member, **pointer;

pointer = new member *[30];

for (int i=0; i<30; i++)
{
    delete[] pointer;                 // Assuming I have already filled this value before
    pointer[i] = new member;
    pointer[i]->x = 1;
    pointer[i]->y = 1;
}
kbw (9488)
No. It's not an array allocation.

Like this.
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for (int i=0; i<30; i++)
{
    delete pointer[i];
    pointer[i] = new member;
    pointer[i]->x = 1;
    pointer[i]->y = 1;
}
benzensulfonic (21)
I tried this and it worked in my loop, but now I can't do anything with the values anywhere else.

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int z;

for (int i=0; i<30; i++)
{
    delete pointer[i];
    pointer[i] = new member;
    pointer[i]->x = 1;
    pointer[i]->y = 1;
}

z = pointer[0]->x;


When I attempt this, it gives me the error, "Unhandled exception at 0x00411fde in Test.exe: 0xC0000005: Access violation reading location 0x00000008."

How can I access the values and what makes it different than what I had before?
firedraco (6243)
Don't delete in your first loop, since there is nothing that was newed you shouldn't need to delete then.
Such (8)
I think that you don't want this:
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struct example
{
    int x
    int y
} member, **pointer;

pointer = new member *[30];
for (int i=0; i<30; i++)
{
    delete pointer[i];
    pointer[i] = new member;
    pointer[i]->x = 1;
    pointer[i]->y = 1;
}

But this:
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struct example
{
    int x
    int y
} member, **pointer;

pointer = new example *[30];
for (int i=0; i<30; i++)
{
    pointer[i] = new example;
    pointer[i]->x = 1;
    pointer[i]->y = 1;
}
for (int i=0; i<30; i++)
    delete pointer[i];
delete []pointer;
Last edited on
Terron (11)
Dynamic memory leak?

I prefer to use some memory leaks detection tools to localize memory leaks, for ex.: Deleaker (http://deleaker.com)
hidipak (8)
Hello George,
Basic ans is,
-for every pointer like you have **pointer, you need to allocate memory using 'new' before you use it. [In your case you have two pointers **, so as per such's code, you need to use new two times and hence delete]
-for any object allocated using 'new' you need to 'delete' them.
-If you don't delete, there will be a memory leak.
-for class you can delete class object using destructor (having delete code for that object)

D.
Last edited on
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