Question

I made a small program that looked like this:

void foo () {
  char *str = "+++"; // length of str = 3 bytes
  char buffer[1];

  strcpy (buffer, str);

  cout << buffer;
}

int main () {
  foo ();
}

I was expecting that a stack overflow exception would appear because the buffer had smaller size than the str but it printed out +++ successfully… Can someone please explain why would this happened ?

Thank you very much.

Answer 1

Undefined Behavior(UB) happened and you were unlucky it did not crash.
Writing beyond the bounds of allocated memory is Undefined Behavior and UB does not warrant a crash. Anything might happen.
Undefined behavior means that the behavior cannot be defined.