subtraction

I just have a simple question about arrays in C What's the best way to remove elements from an array and in the process make the array smaller. i.e the array is n size, then I take elements out of the array and then the array grows smaller by the amount that I removed it from. basically I'm treating the array like a deck of cards and once I take a card off the top of the deck it shouldn't be there anymore. EDIT: I'm going to drive myself crazy before the end of the day, thanks for all the help I'm trying the value swapping thing but it's not working right. #include <stdio.h> #include <string.h

I'm trying to write a Date class in an attempt to learn C++. I'm trying to find an algorithm to add or subtract days to a date, where Day starts from 1 and Month starts from 1. It's proving to be very complex, and google doesn't turn up much, Does anyone know of an algorithm which does this? The easiest way is to actually write two functions, one which converts the day to a number of days from a given start date, then another which converts back to a date. Once the date is expressed as a number of days, it's trivial to add or subtract to it. You can find the algorithms here: http://alcor

I have been looking for an answer for a few hours now, but I can't find one. I'm writing a simple script . The user sets their work start and end time. So, for example, somebody is working from 8:00 to 16:00. How can I subtract this time to see how long the person has been working? I was experimenting with strtotime(); but without success... A bit nicer is the following: $a = new DateTime('08:00'); $b = new DateTime('16:00'); $interval = $a->diff($b); echo $interval->format("%H"); That will give you the difference in hours. If you get valid date strings, you can use this: $workingHours =

Possible Duplicate: How can I divide each row of a matrix by a fixed row? I'm looking for an elegant way to subtract the same vector from each row of a matrix. Here is a non elegant way of doing it. a = [1 2 3]; b = rand(7,3); c(:,1) = b(:,1) - a(1); c(:,2) = b(:,2) - a(2); c(:,3) = b(:,3) - a(3); Also, the elegant way can't be slower than this method. I've tried c = b-repmat(a,size(b,1),1); and it seems slower. EDIT: The winner is this method. c(:,1) = b(:,1) - a(1); c(:,2) = b(:,2) - a(2); c(:,3) = b(:,3) - a(3); EDIT: More methods, and tic toc results: n = 1e6; m = 3; iter = 100; a = rand(1