On Tue, Oct 22, 2013 at 9:40 AM, Steven D'Aprano <
steve+comp.lang.pyt...@pearwood.info> wrote:
> On Tue, 22 Oct 2013 15:39:42 +0000, Grant Edwards wrote:
>
> >> No, I was thinking of an array. Arrays aren't automatically initialised
> >> in C.
> >
> > If they are static or global, then _yes_they_are_. They are zeroed.
>
> Not that I don't believe you, but do you have a reference for this?
> Because I keep finding references to uninitialised C arrays filled with
> garbage if you don't initialise them.
>
> Wait... hang on a second...
>
> /fires up the ol' trusty gcc
>
>
> [steve@ando c]$ cat array_init.c
> #include<stdio.h>
>
> int main()
> {
> int i;
> int arr[10];
> for (i = 0; i < 10; i++) {
> printf("arr[%d] = %d\n", i, arr[i]);
> }
> printf("\n");
> return 0;
> }
>
> [steve@ando c]$ gcc array_init.c
> [steve@ando c]$ ./a.out
> arr[0] = -1082002360
> arr[1] = 134513317
> arr[2] = 2527220
> arr[3] = 2519564
> arr[4] = -1082002312
> arr[5] = 134513753
> arr[6] = 1294213
> arr[7] = -1082002164
> arr[8] = -1082002312
> arr[9] = 2527220
>
> What am I missing here?
>
The array you made there is an auto variable (stack), not a static or a
global. Try one of the following (neither has been tested):
Static:
int main()
{
int i;
static int arr[10];
for (i = 0; i < 10; i++) {
printf("arr[%d] = %d\n", i, arr[i]);
}
printf("\n");
return 0;
}
Global:
int arr[10];
int main()
{
int i;
for (i = 0; i < 10; i++) {
printf("arr[%d] = %d\n", i, arr[i]);
}
printf("\n");
return 0;
}
As for a reference:
http://stackoverflow.com/questions/1831290/static-variable-initialization
and
http://stackoverflow.com/questions/3373108/why-are-static-variables-auto-initialized-to-zero,
both of which then reference the C++ standard.
>
> --
> Steven
> --
> https://mail.python.org/mailman/listinfo/python-list
>
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