has been on the C + + DELETE and delete[] The difference is not very understanding, today encountered, surf the internet for a moment, came to the conclusion. Make a backup to avoid loss.
C + + tells us to use delete[] when reclaiming the memory space of a single object allocated with new and using Delete to reclaim the memory space of a set of objects allocated with new[]. About new[] and delete[], which are divided into two situations: (1) Allocate and reclaim space for basic data types, and (2) allocate and reclaim space for custom types.
Please see the procedure below.
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#include <iostream>;
using
namespace
std;
class
T {
public
:
T() { cout <<
"constructor"
<< endl; }
~T() { cout <<
"destructor"
<< endl; }
};
int
main()
{
const
int NUM = 3;
T* p1 =
new
T[NUM];
cout << hex << p1 << endl;
// delete[] p1;
delete
p1;
T* p2 =
new T[NUM];
cout << p2 << endl;
delete
[] p2;
}
|
You can run this program on your own, and look at the different results of the delete P1 and delete[] P1, and I won't post the results here.
From the running results we can see that delete P1 in the process of reclaiming space, only p1[0] This object called the destructor, other objects such as p1[1], p1[2] and so on have not called their own destructor, this is the crux of the problem. If you use delete[], all objects will first call their own destructors before reclaiming the space. Basic types of objects do not have destructors, so it should be possible to reclaim the array space of basic types with delete and delete[], but only with delete[] for an array of class objects. For a single object of new, you can only use Delete to reclaim space with delete[]. So a simple use principle is: New and delete, new[] and delete[] corresponding to use.
I understand that when you use Delete to free the memory space requested by new int[], because it has no destructor for the base data type, using delete is the same as delete [], both of which will free up the requested memory space, for a custom data type, with a destructor, with new [ The space to be applied must be freed with delete [], because the destructor of the object array is called one at a time to delete [], then the space is freed, and if you use Delete, only the destructor of the first object is called, and the destructor of the object is not called, then is the space freed??
The difference between delete and delete[] in C + +