how to completely free 2d multidimensional pointer array in c++

Asked Apr 02 '16 at 18:23

Active Apr 02 '16 at 19:04

Viewed 17 times

my question is about how to free completely memory when I new a 2D pointer array in c++, I have used below code, but memory not free completely:

1- int ** a;
2- a = new int*[1000];
3- for(int i =0; i < 1000; i++)
4-  a[i] = new int[1000];

//// some code here

5- for(int i =0; i < 1000; i++)
6-  delete [] a[i];
7- delete [] a;

When I set a break point in line 1, memory in my task manager is 0.4, in line 5 , memory is 4.4, but after line 7 that I delete the variable, memory is 1.1 why memory does not return to 0.4?

edited Apr 02 '16 at 19:04

asked Apr 02 '16 at 18:23

Mahdi Gholami Mehr

_"but memory not free completely"_ Why do you think so? What you have should work well. – πάντα ῥεῖ Apr 02 '16 at 18:24
I want to memory return before new a 2d variable – Mahdi Gholami Mehr Apr 02 '16 at 19:06
As mentioned in the duplicates answer you cannot take in account what's measured in the task manager, it's useless information in this case. Your code is fine, and releases the memory, to be reused for new variables. – πάντα ῥεῖ Apr 02 '16 at 19:08
ok, but if i use many pointer like this, my program will crash – Mahdi Gholami Mehr Apr 02 '16 at 19:30
Why are you using raw pointers at all? Let e.g. `std::vector>` manage this for you, it's less error prone. – πάντα ῥεῖ Apr 02 '16 at 19:32
I have used this before, but my program needs many processing and after a few running, memory overflow would happen and my program would crash – Mahdi Gholami Mehr Apr 02 '16 at 19:38
Another way of handling two dimensions is to use a simple `std::vector` and indexing by sections of rows and columns (calculate the "real" index). – πάντα ῥεῖ Apr 02 '16 at 19:41
I have used this before, but when the array is big, it gets more time than previous way – Mahdi Gholami Mehr Apr 02 '16 at 19:50

how to completely free 2d multidimensional pointer array in c++

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