>>>>> Glynn Clements <[EMAIL PROTECTED]> writes:
>>> Doesn't C require an explicit initial value for `initialized' here?
>>> Well, as it is a static variable it will be initialised to zero.
>> Oh, never knew C has such a feature. (Still, it may make sense to
>> add an explicit initializer for the sake of clarity.)
> If you add an explicit initialiser, the variable will be placed in
> the data segment.
> Variables which are implicitly initialised to "zero" (i.e. any global
> variables and "static" local variables lacking an explicit
> initialiser) are placed in the BSS segment. As the entire BSS segment
> is zero, its contents don't need to be stored in the resulting binary
> file.
Is this behavior mandated by some standard?
It seems not a very smart decision to require such things. At
least, gcc does, in my opinion, the right thing and puts the
static variable initialized to zero (either explicitly or
implicitly) to BSS:
$ diff -u foo[12].c
--- foo1.c 2008-10-12 22:54:02.281519397 +0700
+++ foo2.c 2008-10-13 22:51:21.117012403 +0700
@@ -1,7 +1,7 @@
int
main ()
{
- static int a;
+ static int a = 0;
return a;
}
$ make CC=gcc foo1 foo2
gcc foo1.c -o foo1
gcc foo2.c -o foo2
$ nm foo1 | grep -F ' b '
00000000005007c4 b a.1609
00000000005007c0 b completed.5959
$ nm foo2 | grep -F ' b '
00000000005007c4 b a.1609
00000000005007c0 b completed.5959
$ diff -u <(gcc -o - -S foo{1,2}.c)
--- /proc/self/fd/63 2008-10-13 22:59:42.420439493 +0700
+++ /proc/self/fd/62 2008-10-13 22:59:42.401668748 +0700
@@ -1,4 +1,4 @@
- .file "foo1.c"
+ .file "foo2.c"
.local a.1609
.comm a.1609,4,4
.text
$
Of course, if there are the compilers that produce different
results in these cases, it may make sense to leave the code in
its present state.
_______________________________________________
grass-dev mailing list
[email protected]
http://lists.osgeo.org/mailman/listinfo/grass-dev
