Formula for difference between two numbers on a wall clock in clokwise direction

Question

It's my first post in math.stackexchange.com. I got a necessity to find out the clockwise difference between two numbers on a wall clock. For example, difference between 12 and 1 is 1 where as the difference between 1 and 12 is 11. Actually what I need is number of clock wise steps required reach number b from number a on a clock. While writing an application, I struck writing this function.

Please help me. Thanks in advance.

can someone tell me why down vote for my question please.... — pinkpanther, May 11 '13 at 13:27
Probably you got caught in the debate on PSQs... or simply because this is a duplicate question. — A.P., May 11 '13 at 13:39

iostream007 · Answer 1 · 2013-05-11T12:22:05.540

1

i am writing a C function

Code

 int clockstep(int a, int b){
    int steps =0;
    if (a<=b)
    {
       steps = b-a;  
     }
     else
    {
       steps = 12-b+a;
     }
  return steps
 }

means you take input from user than compare it if 1st $<=$ 2nd then simply (2nd-1st) is your answer otherwise do (12-2nd+1st).

edited May 11 '13 at 12:22

answered May 11 '13 at 12:05

iostream007

4,529

i have written logic and answer below the code – iostream007 May 11 '13 at 12:26
I think your else clause should be $12+b-a$ since the two answers should agree mod $12$. – robjohn May 11 '13 at 12:43
else is (12-b+a) what is wrong. – iostream007 May 11 '13 at 12:47
$12-b+a\not\equiv b-a\pmod{12}$ Try some numbers and see if you get what you want. For example, $12$ and $1$, then $1$ and $12$. – robjohn May 11 '13 at 12:51
Thanks everybody and thanks @iostream007.Is it not 12-a+b? I think it is! I'm new to this site, can anybody tell me why negative vote for my question? – pinkpanther May 11 '13 at 13:13
@pinkpanther: yes, it should be $12-a+b$. – robjohn May 11 '13 at 13:47

Formula for difference between two numbers on a wall clock in clokwise direction

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