Consequences of Memory allocation and de-alocation...

Hello friends..! I just have a doubt in this concept..
I know it is a must to free up memory at the end, when it is allocated in the beginning of any program.. Otherwise, it would become un-usable junk..
Now, my question is what will be the consequence of this code:

Code:

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#include <iostream>
using namespace std;


class xxx
{
    long long a[1000],b[1000],c[1000],d[1000],e[1000];
};


int main()
{
    long long d=0;
    xxx *a = new xxx[10000];
    xxx *b = new xxx[10000];
   
    //  delete []a;
    //  delete []b;
   
    return 0;
}

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This program uses the allocated memory and if i failed to delete those memory, totally 800,000,000 bytes would become waste...

Will this kind of code much harmful to pc..??
How can i recover those wasted memory...??
Please help me in these issues...!!!!

1. It depends on your OS. Most of them know which program allocated it and so the allocation is ditched when the program is exited.
2. If your OS is not one of those, then a reboot should fix it.

So, when that program is executed, it allocates the memory and when that execution is over, OS will clear it automatically...

Is that what you mean..???

If it depends on OS, then what's on WINDOWS...? windows 7,xp etc..???

Quote:

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Originally Posted by Rehman khan

If it depends on OS, then what's on WINDOWS...? windows 7,xp etc..???

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Windows (at least the versions still supported) will perform the cleanup after the process has terminated. Still, you should not rely on that in your code.

Quote:

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Originally Posted by laserlight

Windows (at least the versions still supported) will perform the cleanup after the process has terminated. Still, you should not rely on that in your code.

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So, even if we didn't use the command 'delete', OS will free up the allocated memory.. fine..

Now, can you tell me what are the ways to make that allocated memory to be permanent...?
I mean, it should not be erased at the end of the execution. Is it possible.???

Why would you want to do that?

Quote:

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Originally Posted by Rehman khan

Now, can you tell me what are the ways to make that allocated memory to be permanent...?
I mean, it should not be erased at the end of the execution. Is it possible.???

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Save it to a file.

Whilst the OS will definitely reclaim the memory, it's important to remember that the destructors will NOT be called if you do not call delete.

So if your class allocated other resources (files, semaphores, device handles and so forth), then things could be less clear cut.

Cleaning up when you're done (as a habit) means you're more likely to do it when it matters most.

Quote:

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Now, can you tell me what are the ways to make that allocated memory to be permanent...?

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I'm terrified by what this implies; I remember bad "TSR" programs.

Soma

Quote:

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Originally Posted by GReaper

Why would you want to do that?

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Actually, i don't want to do such a thing...!!!Learning is not a sin, right..??? :) :) B)

Quote:

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Originally Posted by oogabooga

Save it to a file.

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It's better for me to understand, if your answer is more specific..

What should i save...???

Quote:

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Originally Posted by Rehman khan

What should i save...?

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What do you want to save?

Quote:

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Originally Posted by Salem

Whilst the OS will definitely reclaim the memory, it's important to remember that the destructors will NOT be called if you do not call delete.

So if your class allocated other resources (files, semaphores, device handles and so forth), then things could be less clear cut.

Cleaning up.....

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Well, first thanks for your response...!!!
But, you see, i'm not a PRO in c++... So, can you make me understand what you told...???? Here, where is the destructor came from....???
and what's the relation between destructor and delete as you said...???

Quote:

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Originally Posted by Rehman khan

But, you see, i'm not a PRO in c++... So, can you make me understand what you told...???? Here, where is the destructor came from....???
and what's the relation between destructor and delete as you said...???

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I think you should work through some introductory material on C++. For example, Accelerated C++ by Koenig and Moo. Comprehensive structured learning is not a sin.

Quote:

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Originally Posted by laserlight

I think you should work through some introductory material on C++.............

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Thank you..!! But, that's the book, i'm using for the past 3 months..!!!!

All I have is, only one confusion.!!! If i didn't use 'delete' OS itself will clean the allocated memory. Fine..!! Then how can i make that allocated memory to be permanent...???

Please i need answer for this question..

As you were told, write a file. A file is formatted data stored on the hard disk, so it is permanent allocation in that sense.

Quote:

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All I have is, only one confusion.!!! If i didn't use 'delete' OS itself will clean the allocated memory.

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Yes. But many destructors do more than simply release memory, so make sure that they are called with delete if you use new. Any additional steps a destructor takes would not be automatically performed by the OS in a memory-leak kind of situation.

If saving to a file is not the answer you're seeking, maybe you should explain exactly what you're trying to do.

There's something very strange here: Who can read Koenig and Moo for three months and then ask "what's a destructor"?

> Please i need answer for this question..
Then there's the almost obsessive zeal in knowing how to make memory persist after the process has ended. This is like "I've just made a paper airplane, now tell me all about jet engines".

Perhaps if you explained the nature of the problem(*) you're trying to solve (as opposed to saying - the answer to this problem is persistent memory, tell me how to do it), then perhaps you would get better answers.

My your own admission, you really don't know enough to figure out alternative answers to the problem.


(*) Be warned, if this is "malware" or "hacking" (see the rules), you're not going to get any further on this forum.