MetaTrader 4 Build 574 with Updated MQL4 Language and Market of Applications Released - page 22

In MT4, it turns out that this:

int test_int = ExampleTickCount

is not the same as this:

int test_int = (int)ExampleTickCount

If you don't do an explicit cast, then the new variable "remembers" that its value used to be unsigned, and affects future casts.

I don't know about Java, but what you are describing is normal - if nevertheless surprising - for C++. In effect, you can't fully re-declare public functions as private because you can indeed still invoke them via a cast of the base class.

http://stackoverflow.com/questions/5753833/c-overriding-public-private-inheritance

Because - unless I've got the testing of this wrong - in the first example test_int doesn't just hold a value; it also carries with it a memory of a previous use and version of that value. It's a sort of "homeopathic" int, which remembers that it used to be a uint in the same way that homeopathic remedies are supposed to remember the substance which now exists only as 1 atom per squillion particles.

Plus the fact that, as a default position, I'd expect MT4 to be similar to C.

Yes the question I deleted was, why does typcasting it to a long not turn it to a negative value too ? But I thought your explanation covered that ...

Here is my test script I'm using GetTickCount() because it returns a uint value.

void OnStart()
  {
   uint uticks = GetTickCount();
   int iticks = uticks;
   long lticks = uticks;

   Print("uticks = ",uticks);
   Print("iticks = ",iticks);
   Print("lticks = ",lticks);
  }

Output:

• uticks = 3867100516
• iticks = -427866780
• lticks = 3867100516
  
  

Perhaps the conclusion Raptor and I came to earlier was the correct one, the uint is a positive value to big for an int so the int wraps around to a negative value, whereas it is not too big for a long so the long remains the same value as the uint ?

Well I know only mql4. I've finished a tutorial on C++ about 2 weeks ago. I went C++ because "my" impression was that mql4+ would be closer to C++.

I wonder if anyone who visits know how C++ handles it........

I believe that mql4+ have some sort of garbage_collector / virtual memory envrionment and maybe thats why it keeps the foot_prints but I'm just speculating.

Anyways I see 2 different actions ... having 2 different results ... and I don't think theres a Right / Wrong with that.

Just perhaps what someone expects vs how its implemented.