[vox] things that really suck about C!

[Carl Boettiger]

On Sun, Feb 28, 2010 at 6:35 PM, Brian Lavender <brian at brie.com> wrote:

> I think if anything, C has been a certain detriment to the field of
> computer science!
>
> One calls a function and the arguments are passed by value. Call a
> function with an array as an argument, and feel free to modify its
> contents!
>
> so declaring an array as const prevents this, func(const double * a).  I
understand that this also helps the compiler make optimizations it cannot do
when you don't use const.  I think you could still modify the contents of
the array by first copying the pointer though,

double * b = a;
b[i] = something new.

So there's also the modifier "restrict", which I believe would prevent this,
and again helps out the compiler do smart things.  Others can probably
confirm/correct this?  Is it good practice to use these modifiers as often
as possible/appropriate?


> Certainly, C++ added the idea of reference, but I think Pascal
> simplifies these concepts much better. Yet, Pascal seems to be relegated
> to the status as a legacy language!
>
> brian
>
>
> #include <stdio.h>
>
> #define CAP 10
>
> void mod_array(int a[])
> {
>  a[2] = 5;
> }
>
> void trychange(int a)
> {
>  a = 2;
> }
>
> void reallychange(int *a)
> {
>  *a = 2;
> }
>
> int main() {
>  int b[CAP];
>  int c;
>  int i;
>
>  printf("Load array and change a value\n");
>  for (i=0; i < CAP; i++)
>    b[i] = i + 20;
>
>
>  mod_array(b);
>
>  for (i=0; i < CAP; i++)
>    printf("b[%d] has value of %d\n",i,b[i]);
>
>  c = 10;
>
>  printf("c has a value of %d\n",c);
>  trychange(c);
>
>  printf("c has a value of %d after trychange(c)\n",c);
>
>  reallychange(&c);
>
>  printf("c has a value of %d after reallychange(&c)\n",c);
>
>
> }
>
> --
> Brian Lavender
> http://www.brie.com/brian/
>
> "There are two ways of constructing a software design. One way is to
> make it so simple that there are obviously no deficiencies. And the other
> way is to make it so complicated that there are no obvious deficiencies."
>
> Professor C. A. R. Hoare
> The 1980 Turing award lecture
> _______________________________________________
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> http://lists.lugod.org/mailman/listinfo/vox
>



-- 
Carl Boettiger
Population Biology, UC Davis
http://two.ucdavis.edu/~cboettig
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