c ++ delete [] 2d数组导致堆损坏

Question

When I tried to delete a 2-D array in C++ , it caused an error in Visual Studio 2017:

HEAP CORRUPTION DETECTED: after Normal block (#530965) at 0x0ACDF348.
CRT detected that the application wrote to memory after end of heap buffer.

The code is below:

const int width = 5;
const int height = 5;

bool** map = new bool*[height];
for (int i = height; i >= 0; --i) {
    map[i] = new bool[width];
}

for (int i = height; i >= 0; --i) {
    delete[] map[i];
}
delete[] map; // error occurs here

What's wrong with the code please?

Answer 1

You're getting out of the bound of the array; which leads to UB. Note that the range is [0, height) , the elements are numbered 0 , … , height - 1 .

Change the two for loop from

for (int i = height; i >= 0; --i) {

to

for (int i = height - 1; i >= 0; --i) {

---

^{PS: In most cases we don't need to use raw pointers and new / delete expression manually, you can just use array (not with raw pointer), or std::vector and std::array , or smart pointers instead.}