You are right, I omitted the overflow condition in the code, and it can be
workarounded as follow:
int get_max(int a,int b)
{
long long divisor = (long long)a-(long long)b;
int array[2];
array[0]=a;
array[1]=b;
return array[( divisor & (ULLONG_MAX/2+1U) ) >> ((sizeof(long
long)*8)-1)];
}
As far as I am concerned, this question is rather an excersice than what
will be used in the real engineering environment. It forces the coder to
implement an "if(a<b){....}" expression with high level programming language
C rather than the compiler generated assembly. In the assembly we can get
the value of the status-register, which will help us know the overflow in
the last caculation. but with pure C it is hard to get this valuable
information(if I am wrong please correct me).So it's impossible to implement
a perfect "if(a<b){...}" without knowing the processor details. And it's
impossible for a program caring the processor details be portable!
If we see the question as an excersice for "if(a<b){....}" and an
interesting puzzle, it is worthwhile to have a try and have some fun.
The "if(a>b){return a;}..." like impl is surely not stupid for the
real-world engineering, but it is surely not a clever answer for a puzzle,
right?
Anyway, I am with this answer just because that I am with this
sounds-interesting-question, not means that I support this kind of coding
standard in the project. I take your point that in engineering practice,
simply is the best.
BTW, is there any perfect solution to implement the "if(a<b){....}" without
any Relational Operator?
-----邮件原件-----
发件人: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
发送时间: 2007年12月8日 22:47
收件人: [EMAIL PROTECTED]
抄送: [EMAIL PROTECTED]
主题: Re: greatest of two numbers
On Dec 8, 9:35 am, James Fang <[EMAIL PROTECTED]> wrote:
> Thanks for your correction...
>
> int get_max(int a,int b)
> {
> int array[2];
> array[0]=a;
> array[1]=b;
> return array[( (a-b)& (UINT_MAX/2+1U) ) >>
> ((sizeof(int)*8)-1)];}
>
> int main()
> {
> printf("%d\n",get_max(-190,-100));
> printf("%d\n",get_max(10000,100));
> printf("%d\n",get_max(99,199));
>
> }
Still wrong. With your code,
printf("%d
\n",get_max(2147483647,-1));
will print -1 as the answer.
Your entire attempt is stupid, and the OP's requirement
is stupid. Your whole attempt is pointless,
and encourages stupid programming.
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Algorithm Geeks" group.
To post to this group, send email to algogeeks@googlegroups.com
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at http://groups.google.com/group/algogeeks
-~----------~----~----~----~------~----~------~--~---
