Question

I have a php web site, and here I need to create a page to enter exam details of a student. There are 5 Subject in one exam. Each subject has exam date, starting time and end time

I.e.

Date: 02-nov-2012 
Start time: 2.30 pm
End time: 4.30 pm 

I have to check the duplication of the exam date time….i.e. any other subjects which don’t have the similar date time also if one subject has

Exam Date:  02-nov-2012 
Start time: 3.00.pm 
End date: 5.00 pm 

Must be avoided. It’s invalid
Another subject has

Exam Date:  02-nov-2012 
Start time: 9.00.am 
End date: 2.00 pm 

It’s a valid

I think it’s clear… I don’t know to explain further in details….
I don’t know to validate this in php

Answer 1

$errors = array();

for ($i = 0; $i < count($exams); $i++) {
  for ($j = $i+1; $j < count($exams); $j++) {
    if (($exams[$j]['start_time'] >= $exams[$i]['start_time'] && ($exams[$j]['start_time'] <= $exams[$i]['end_time']) ||
        ($exams[$j]['end_time'] >= $exams[$i]['start_time'] && ($exams[$j]['end_time'] <= $exams[$i]['end_time'])) {
      $errors[] = "<li>Exams $i and $j overlap.</li>";
    }
  }
}

if ($errors) {
  echo "There were conflicts:<br><ul>\n ", join("\n ", $errors), "\n</ul>\n";
} else {
  echo "Congratulations, no conflicts!\n";
}