Re: Why is &array[0] @safer than array.ptr?

[Rene Zwanenburg via Digitalmars-d-learn]

On Tuesday, 24 January 2017 at 11:38:16 UTC, Jonathan M Davis 
wrote:
Likely because it does bounds checking, so you at least know 
that it's not null. But I don't see why that would really 
improve much considering that the odds are that you're really 
going to be accessing far more than just the first element with 
the pointer. It seems _slightly_ better from a safety 
perspective but only slightly. So, I don't know what the point 
is in suggesting it as an alternative.

- Jonathan M Davis

Pointer arithmetic is forbidden in @safe code so that's not a 
problem. The reason this was introduced was indeed bounds 
checking. For example:

@safe:

int parse(ref char[] input)
{
  // Pop all numeric characters from the front of the input slice 
and convert to int
}

void main()
{
  auto input = "123".dup;
  parse(input);
  // Since all numeric chars have been popped, input is now 
effectively input[$ .. $].
  // This means input.ptr is pointing past the end of the array.
  writeln(input.ptr); // Out of bounds access
}