PHP for loop dates - php

Question

I'm trying to create a for loop where I specify a beginning date and end date and I want to pull a random mix of dates where each date will always be later than it predecessor and earlier than the next number.
There is no pre-defined set of dates I need, I may have 10 - I may have 100 or 1000 as long as they exist within the start and end dates.
Example:
2015-01-15 08:06:00
2015-01-15 15:23:42
2015-01-16 06:03:00
.........
.........
2015-01-20 08:18:32
This is what I have (which is wrong):
$start = strtotime('2015-01-10 08:00:00');
$end = strtotime('2015-01-20 10:57:59');
for ($i=$start;$i<$end;$i++) {
//Current time + Anywhere between 1 hour and 3 days
$x = $i + (int)rand(3600,259200);
echo "<p>" . date('Y-m-d H:i:s', $x) . "</p>";
}
In my tests, I'm not getting any results...I believe the loop is running infinitely...or something else is wrong.
Can anyone help?

Answer 1

If I gather your question correctly, it seems like you're going about it the wrong way. The easiest way would be to generate random times in a range (between $start and $end) and then sort them. That way you don't have to guess at how much time-space you have left when choosing a random interval.
$start = strtotime('2015-01-10 08:00:00');
$end = strtotime('2015-01-20 10:57:59');
$num_randoms = 10;
for ($i=0;$i<$num_randoms;$i++) {
$dates []= (int)rand($start,$end);
}
sort($dates);
foreach ($dates as $x) {
echo "<p>" . date('Y-m-d H:i:s', $x) . "</p>";
}

Answer 2

You assumed that those two will be your dates
$start = strtotime('2015-01-10 08:00:00');
$end = strtotime('2015-01-20 10:57:59');
You assumed also that you will use specific range of seconds for pseudorandom number generation
$min = 3600; // 1 hour
$max = 259200; // 72 hours (3 days)
The first step you need to do is to reduce the ending number of seconds with the range maximum. This will assure you that latter date will be before the specified date
$end -= $max;
And at the end here is the proper loop. I used while loop because it is more readable.
while ($start < $end) {
$start += (int) mt_rand($min, $max); // add the generated value to the start seconds
echo date('Y-m-d H:i:s', $start);
}
PS. Notice I used the mt_rand function

Answer 3

Use the milliseconds representation of you date value. Pseudo-code is as follows:
Convert the start date to its milliseconds representation sm
Convert the end date to its milliseconds representation em
For i = 0 up to n, n is the number of dates...
3.1 randomize some value between sm and sm + offset
3.2 convert the generated value to its date object representation
3.3 assign sm = sm + offset and check if sm < em
offset is the size of the sampling interval, offset <= (em - sm) / n