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

[Andres R. <lo...@ho...>]

Yes. Variable sized arrays are GNUC extension.
If you use =96ansi or =96pedantic switches on commandline, you get only
warning:
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test.cpp: In function `int main()':
test.cpp:12: warning: ANSI C++ forbids variable-size array `myArray'
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Andres
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-----Original Message-----
From: dev...@li...
[mailto:dev...@li...] On Behalf Of Abhijit
Shylanath
Sent: Saturday, April 20, 2002 1:21 PM
To: Dev-C++ User Mailing List
Subject: Re: [Dev-C++] Dev-C++ Users Beware!
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Quote Microsoft: "This isn't a bug, it's a feature." Seriously, though,
this is one feature of the GCC compiler (I remember reading about it in
the DJGPP docs). If you're still looking for the compiler to stop when
it encounters non-ANSI code, there must be a command-line options
somewhere.  Yup, here it is... from the Dev-C++ help file.
  _____ =20

- Support all ANSI C standard programs (compiler parameter : -ansi):
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This turns off certain features of GNU C that are incompatible with ANSI
C, such as the asm, inline and typeof keywords, and predefined macros
such as unix and vax that identify the type of system you are using.  It
also enables the undesirable and rarely used ANSI trigraph feature, and
it disables recognition of C++ style // comments.
  _____ =20

But what the hell, GCC is kind of a standard in itself.
mdeth *
m.o.t.o[P.S.Y.C.H.O]=20

http://mudeth.tripod.com | ibr...@bi... | mu...@gm...
----- Original Message -----=20
From: Bob Wilson <mailto:bo...@ph...> =20
To: Dev-C++ User Mailing List
<mailto:dev...@li...> =20
Sent: Saturday, April 20, 2002 3:29 AM
Subject: [Dev-C++] Dev-C++ Users Beware!
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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
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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
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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
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#include <iostream.h>
#include <stdlib.h>
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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";
    }
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    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
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I believe that the dev-c++ compiler is the mingw compiler.=20
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Regards,
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Bob Wilson
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