[Dev-C++] Dev-C++ Users Beware!

[Bob W. <bo...@ph...>]

David,
  An array is not dynamic, the value you pass it at initalization must =
be a constat of some sort.if 'i' were to change during the program some =
weird voodoo (the program will crash,the world will end,etc.) all this =
will hapen because it cannot change the size of an array at =
runtime(reason no. 1 linked lists were created)
I am in the process of learning C++, as Ioannis well knows, and a week =
or so ago I was working on the array chapter. In the past I have done =
most of my programming in pascal, and every pascal compiler I have used =
will not compile an array if the size of the array is a variable, i.e., =
no dynamic arrays. Just fooling around I modified the simple little C++ =
array program to define an array with a variable. I had not done any =
research but was confident that the compiler would flag an error and =
bail out.=20

Not So! the program compiled and ran allowing me to change the size of =
the array. I tested the bounds of the program and could build quite =
large arrays. the size_of function always returnd the correct size of =
the array. I was really surprised because that it worked. I have not =
employed the technique in any real world program, because I felt that it =
would be much safer with pointers and linked lists.=20

Your message above confirmed what I suspected but had not taken the time =
to investigate. Stroustrup says:
  The number of elements of the array, the array bound, must be a =
constant expresseion (=A7C.5)
Paragraph C.5 says in part:
  A constant expression evaluates to an integral of enumeration =
constant. Such an expression is composed of literals, enumerators, and =
const initialized by constant expressions. < . . . > Intuitively, =
constant expressions are simple expressions that can be evaluated by the =
compiler before the program is linked and starts to run.
That tells me that the compiler should have caught this and bailed out =
rather than compiling, linking, and running this program:=20

  #include <iostream.h>
  #include <stdlib.h>

  int main
  {
      int arraySize =3D 1;
      std::cout << "Enter the size of the array: ";
      std::cin >> arraySize;
      if (!(arraySize > 0))
      {
          system("pause");
          return 0;
      }
      int myArray[arraySize];
      int arrayLength =3D sizeof(myArray)/sizeof(myArray[0]);
      for (int i=3D0; i < arrayLength; i++)     // 0 to arrayLength-1
      {
          myArray[i] =3D (i + 1) * 2 + 1;
      }
      for (int i=3D0; i< arrayLength; i++)     // 0 to arrayLength-1
      {
          std::cout << i << ": " << myArray[i] << "\n";
      }
     =20
      system("pause");
      return 0;
  }
The faulty compiler is the one used by Bloodshed. Visual C++ 6.0 caught =
the error. That is the second and most serious problem I have found with =
the compiler used by the dev-c++ environment. It appears it will =
properly compile ANSI standard code, but it will also compile code that =
is clearly outside of the standard.=20

I believe that the dev-c++ compiler is the mingw compiler.=20

Regards,

Bob Wilson