On Mon, 14 Jan 2013 19:29:19 +0800 GHui wrote:
> I code the following code.
> --------------------------
> #include <stdio.h>
> int main(int argc,char **argv)
> {
> float f[2]={4.0, 37.4};
> printf("%.2f %.2f\n",f[0],f[1]);
> printf("%d %.2f\n",f[0],f[1]);
> }
>
> And it output is following.
> -------------------------
> 4.00 37.40
> -1 4.00
>
> I confuse that f[1] is 4.00 at the second line.
> Any help will be appreciated.
>
Off the top of my head: the second printf pulls the argument for "%d"
from the general set of registers, while the one for "%.2f" is taken
from the SSE registers. At least on amd64. For x86 it has something to
do with how the float arguments are placed on stack (unlike int-s). You
can probably get a better image with:
$ objdump -D -C -l -j .text <binary> | vim -
--
Mihai Donțu
