|
|
|
I had the code somewhere for fiquiring when a year was a Leap Year, but I can't find it anywhere(C++). Could someone please show me how to figuire it(MFC)?
Thanks in advance.
A C++ programming language novice, but striving to learn
|
|
|
|
|
not code but this is how to calculate leap years:
A year will be a leap year if it is divisible by 4 but not by 100. If a year is divisible by 4 and by 100, it is not a leap year unless it is also divisible by 400.
Thus years such as 1996, 1992, 1988 and so on are leap years because they are divisible by 4 but not by 100. For century years, the 400 rule is important. Thus, century years 1900, 1800 and 1700 while all still divisible by 4 are also exactly divisible by 100. As they are not further divisible by 400, they are not leap years.
Why is common sense not common?
Never argue with an idiot. They will drag you down to their level where they are an expert.
Sometimes it takes a lot of work to be lazy
Individuality is fine, as long as we do it together - F. Burns
|
|
|
|
|
Do you need to calculate leap year or do you need to determine if leap year to perform other calculations (Age, difference, etc...)?
If yes to first, www.wikipedia.org has all the mathematical and historical details.
If yes to the latter, use COleDateTime as it will do all the calculations for you. It can be used to validate a date as well.
|
|
|
|
|
In the program I'm writing I complete several editboxes with dates according to the need. I need to know before I fill-in the dates if it is a leap year; otherwise the key element in the program will fail. I must know exactly(programmatically) whether the user is in a leap year or not;
A C++ programming language novice, but striving to learn
|
|
|
|
|
Larry Mills Sr wrote: ...if it is a leap year;
What is it? Regardless, if "it" is a valid year, just mod it with 4, and 100 (and 400 if necessary) to determine its leapness.
"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
|
|
|
|
|
I know I can trigger (from C++) the current user to be logged out of Windows (XP/Vista). Is it possible to SWITCH users either by triggering a logout/login or by triggering a fast user switch without the user having to do anything like enter their password, etc.?
I would like to have a UI where a user can choose to switch to another user in one step (assuming they know the target password) without going through the Windows login screen.
Any ideas?
Thanks,
Barry Etter
Barry Etter
|
|
|
|
|
|
Hi,
I want a very fast and optimized, yet, open source quicksort implementation.
We have a real-time system and the bottle-neck is qsort, STL qsort is even far worse than ours, maybe because of the "compare" function calls that take place.
BTW, our qsort algorithm is written by an average programmer so it is not likely to be optimum.
Thanks,
Mohammad
And ever has it been that love knows not its own depth until the hour of separation
|
|
|
|
|
Is the bottleneck the quicksort itself or the comparison or swap operations ?
If your data is already nearly sorted, quicksort will be slow(er); it will will get to a complexity of N instead ( N log N )
Slightly off-topic without knowing the details, but do you need to do a quicksort at all ? do you have that much information that you need
to sort in "real-time" ? is your data unsorted that you always need to re-sort it ?
|
|
|
|
|
Yes, the bottle-neck is qsort itself, the comparison is done for floating-point data, and swapping is just some part of qsort.
My data aren't sorted at all, almost random..and I do need to sort my data before I can process them.
Thanks,
Mohammad
And ever has it been that love knows not its own depth until the hour of separation
|
|
|
|
|
Have you looked at the code in ...\VC98\CRT\SRC\Qsort.c file for ideas?
"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
|
|
|
|
|
Thanks for the reply.
No, I haven't.. but I will do this now..
Thanks 
And ever has it been that love knows not its own depth until the hour of separation
|
|
|
|
|
Have you tried the implementation in "Fundamentals of Program Design and Data Structures with C++" by Kenneth A. Lambert and Thomas L. Naps?
(Pages 398-399)
A large number of quicksort implementations appear to swap too much. Lambert and Naps minimize the swapping in their implementation. This could be of value since, to the best of my knowledge, a memory write is more expensive than a memory read. Correct me if I'm wrong though.
|
|
|
|
|
C runtime qsort is slow?
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
[my articles]
|
|
|
|
|
Isn't it that one in the STL? yes it is slower than an ordinary qsort algorithm, this might be due to the excessive function calls that call the "compare" function. we use simple ">" and "<" operators instead of function calls
And ever has it been that love knows not its own depth until the hour of separation
|
|
|
|
|
Try using std::sort[^]. Here's an example:
#include "stdafx.h"
#include <ctime>
#include <cstdlib>
#include <iostream>
#include <vector>
#include <iterator>
#include <algorithm>
using namespace std;
int main(int argc, char* argv[])
{
vector<int> numbers;
srand(static_cast<unsigned>(time(NULL)));
generate_n(back_inserter(numbers), 10, &rand);
cout << "Not sorted:" << endl;
copy(numbers.begin(), numbers.end(), ostream_iterator<int>(cout, "\n"));
cout << endl;
sort(numbers.begin(), numbers.end());
cout << "Sorted:" << endl;
copy(numbers.begin(), numbers.end(), ostream_iterator<int>(cout, "\n"));
cout << endl;
return 0;
}
Steve
|
|
|
|
|
I second that suggestion of using std::sort (for the second time, last time you and I together having done an argument on this topic with another CPian, if I remember). There should be no reason why one should use qsort when std::sort can be used.
Nobody can give you wiser advice than yourself. - Cicero
.·´¯`·->Rajesh<-·´¯`·.
Codeproject.com: Visual C++ MVP
|
|
|
|
|
Profile your code and find out where the bottle neck is. STL's sort should work fine.
Steve
|
|
|
|
|
Hi,
The problem I have in using STL's sorting algorithms is as follows:
1. I am not sorting integers but struct objects, but sorting depends only on a float member of the struct.
struct aaa {<br />
int a1;<br />
int a2;<br />
float a3;
};
2. Becoz of this, I have to supply a pointer to a "compare" function that compares two objects.
3. I believe that most of the time is spent during calls to the compare function, I wish I could get rid of the function-call ovrhead.
Any solution?
Thanks
And ever has it been that love knows not its own depth until the hour of separation
|
|
|
|
|
Can you show the "compare" function? You could try making it inline.
Steve
|
|
|
|
|
Yes, I already did. and I also heared that making it static helps the complier optijmize things a little bit better:
<br />
static inline int compare_edges (const void * EDGE1, const void * EDGE2)<br />
{<br />
if(((const struct EDGE*)EDGE1)->reliab > ((const struct EDGE*)(EDGE2))->reliab)<br />
return 1;<br />
else if(((const struct EDGE*)EDGE1)->reliab < ((const struct EDGE*)EDGE2)->reliab)<br />
return -1;<br />
return 0;<br />
<br />
}
And ever has it been that love knows not its own depth until the hour of separation
|
|
|
|
|
Try using a functor[^] instead. Also your "compare" function looks like it's for qsort, not std:sort.
Steve
|
|
|
|
|
Yes, I am still using qsort. I'll see what I can do with a functor.
Thanks alot
And ever has it been that love knows not its own depth until the hour of separation
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
