On Tue, Mar 4, 2008 at 12:01 PM, debasish deka
<[EMAIL PROTECTED]> wrote:
> Hello All,
> A few days back I attended Huawei Interview where the following code's
> output was expected:
> unsigned char i;
> for(i=0;i<2000;i++)
> printf("\t%d",i);
> A simple thinking gives the output to be :
> values from 0 to 255.
> When I checked it out on my Dev-C++ it showed counting exactly up to 2000.
You compiler isn't doing what it should then.
> Now my doubt it if a character variable occupies one byte then it should
> count upto 255 only
On most computers this is what it should be doing. (The exceptions
being when a char has more than 8 bits.)
> then it should overflow. Thus the result should be either counting upto
> 255(and stop)
Erm - nope.
> or ending in an infinite loop counting each time up to 255.
That's what it should be doing.
> Then why and how it is counting uoto 2000 (exactly).
Pass. Your compiler may be broken.
> Again in a forum it was asked to give the output of the following codes ::
> unsigned i;
> i=100*400;
> printf("\n%d\n",i);
> Strangely again, the output was exactly 40000as opposed to + 32767 or showing
> any sort or overflow, since the range of unsigned int ranges from- 32767 to
> 32768.
That is one possible range. The Standard dictates minimum ranges only
- compilers are allowed to exceed them.
> Now my question is how the compiler manages to tackle such situations, I
> mean what
> mechanism does the compiler the aplies in such a situation...
Depends on your compiler, and the value of CHAR_BIT (8 on my system.)
I get the following:
[EMAIL PROTECTED] tmp]# cat t.c
#include <stdio.h>
int main(void){
unsigned char c;
for(c=0; c<4000; c++){
printf("%i\n", c);
}
return 0;
}
[EMAIL PROTECTED] tmp]# make t
cc t.c -o t
t.c: In function 'main':
t.c:5: warning: comparison is always true due to limited range of data type
Note the warning.
And running t gives me cycles of 0-255 then it starts at 0 again, and
goes on forever.
--
PJH
http://shabbleland.myminicity.com
