Calling delete on variable allocated on the stack

Question

Ignoring programming style and design, is it "safe" to call delete on a variable allocated on the stack?

For example:

   int nAmount;    delete &nAmount; 

or

class sample { public:     sample();     ~sample() { delete &nAmount;}     int nAmount; } 

Answer 1

Well, let's try it:

jeremy@jeremy-desktop:~$ echo 'main() { int a; delete &a; }' > test.cpp jeremy@jeremy-desktop:~$ g++ -o test test.cpp jeremy@jeremy-desktop:~$ ./test Segmentation fault 

So apparently it is not safe at all.

Answer 2

No, it is not safe to call delete on a stack-allocated variable. You should only call delete on things created by new.

• For each malloc or calloc, there should be exactly one free.
• For each new there should be exactly one delete.
• For each new[] there should be exactly one delete[].
• For each stack allocation, there should be no explicit freeing or deletion. The destructor is called automatically, where applicable.

In general, you cannot mix and match any of these, e.g. no free-ing or delete[]-ing a new object. Doing so results in undefined behavior.