Member Avatar for kshahnazari

this might be a simple question so accept my appolegises , I am creating a 2 dimetional pointers to int and I want to release the memory at the end but I think I'm doing It all wrong and all of the memory isn't being relaesed.

int **a;
a = new int *[bin->height];
for (int i=0;i<bin->height;i++)
a[i] = new int [bin->width];
for (int i=0;i<bin->height;i++)
            delete [] a[i];
            delete a;

am I doing it right ?

Edited by kshahnazari
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  • Latest Post Latest Post by rubberman
Member Avatar for deceptikon

Very close, and conceptually you've got it perfect. The only problem is a mismatch of new[] and delete when releasing a. This is what you want:

int **a;

a = new int *[bin->height];

for (int i=0;i<bin->height;i++)
    a[i] = new int [bin->width];

for (int i=0;i<bin->height;i++)
            delete [] a[i];

delete [] a;

When using new, you should have a corresponding delete. When using new[], you should have a corresponding delete[].

Member Avatar for rubberman

This is when having a class to handle this cruft is called for. That way, you can deal with the new/delete cruft in the constructors/distructor and when you are done with the instance, just delete the class instance. IE,

void 2darrayfunct(size_t height, size_t width)
{
    2darray array = 2darray(height, width);
    // Do stuff with array here.
    .
    .
    .
    // Now, done with array.
}

Leaving the function, the array is automatically destroyed as it has gone out of scope. Simple, complete, no leaks (assuming the 2darray class destructor is properly implemented).

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