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The Yak Corral

function problem

Author

Topic

ace333
Starting Member

11 Posts

Posted - 2005-09-20 : 13:48:17

Anyone know what language this function is in and what its doing....
I think its trying to reset the time inputted to zero .....

any help .... and can any1 spot any of the errors in it....

time_t normalise(time_t input_time)
{

bool finished;

// This produces a formatted time string like:
// Thu_Nov_24_18:22:48_1986
string str_time = format_time( input_time );

while( str_time.substr(1,3) != "Sun")
{
input_time -= 24*60*60;
str_time = format_time( input_time );
}

while( str_time.substr(11,2) != "00" )
{
input_time -= 60*60;
str_time = format_time( input_time );
}

while( str_time.substr(14,2) != "00")
{
str_time = format_time( input_time );
input_time -= 60;
}

while( str_time.substr(17,2) != "00")
{
input_time -= 1;
str_time = format_time( input_time );
}

return input_time;
}

elwoos
Master Smack Fu Yak Hacker

2052 Posts

Posted - 2005-09-20 : 14:03:44

Looks like a variant of C to me!!

As for what it's doing - never did quite grasp the intricacies of C

steve

Facts are meaningless. You could use facts to prove anything that's even remotely true!

Kristen
Test

22859 Posts

Posted - 2005-09-20 : 14:07:37

It looks like a completely crap routine to roll a time value back to midnight on Sunday-last!

Completely pointless.

ace333: tell the interviewer that you think it would be done more efficiently using a Tally table. If he doesn't know what one of those is suggest he reads some books by Joe Celko.

Kristen

Arnold Fribble
Yak-finder General

1961 Posts

Posted - 2005-09-20 : 15:44:03

There are 7 days in a week.
19700101 was a Thursday.
Shouldn't it be something like this?


time_t normalise(time_t input_time) {
  return input_time - ((input_time+345600)%604800+604800)%604800;
}

And before you ask, the 2 modulus operators are there because I can't remember whether C is allowed to return negative results for a%b where a is negative.
Also, this assumes a POSIX-compliant lack of leap-seconds!

rockmoose
SQL Natt Alfen

3279 Posts

Posted - 2005-09-20 : 16:19:08

quote:
Originally posted by Arnold Fribble

There are 7 days in a week.
19700101 was a Thursday.
Shouldn't it be something like this?

time_t normalise(time_t input_time) {
return input_time - ((input_time+345600)%604800+604800)%604800;
}

And before you ask, the 2 modulus operators are there because I can't remember whether C is allowed to return negative results for a%b where a is negative.
Also, this assumes a POSIX-compliant lack of leap-seconds!

... thinking for a couple of seconds, thoughtfully removing pipe from mouth ...
"Elementary my dear Watson"

Very nice!
The mark of a genius is simplification, not complication.

jsmith8858
Dr. Cross Join

7423 Posts

Posted - 2005-09-20 : 16:30:23

That is some of the worst code I've ever seen. There quite a few objects that we need definitions before -- this depends on what time_t is (a struct? a class?) and what the function format_time() returns.

spirit1
Cybernetic Yak Master

11752 Posts

Posted - 2005-09-20 : 18:01:12

if i remember my c++ days correctly time_t is a struct.

Go with the flow & have fun! Else fight the flow