重叠两个日期/时间范围-PHP

Question

I am trying to determine if two sets of date/time range overlap or not --- returning BOOLEAN value.

Consider the following cases:

NOTE : I turn each date/time string below (eg 24-JAN-17 07:00 ) to timestamp using strtotime()

Expression used for each case is: $isOverlapping = (s1 < e2 && s2 < e1)

Case 1 :

Let (s1, e1) be defined as (24-JAN-17 07:00, 24-JAN-17 17:00)

Let (s2, e2) be defined as (24-JAN-17 16:30, 24-JAN-17 17:30)

Result: TRUE (which is correct)

---

Case 2 :

Let (s1, e1) be defined as (24-JAN-17 07:00, 24-JAN-17 17:00)

Let (s2, e2) be defined as (24-JAN-17 16:30, 25-JAN-17 07:00)

Result: TRUE (which is correct)

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Case 3 :

Let (s1, e1) be defined as (24-JAN-17 07:00, 24-JAN-17 17:00)

Let (s2, e2) be defined as (24-JAN-17 17:00, 25-JAN-17 07:30)

Result: FALSE (which is INCORRECT)

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It is my understanding that it does this because (in case of #3 above), it overflows into the next day... but if that is the case, why does it work for Case 2 ? (is it because the overlap happens on the same day, contrary to Case 3 ?)

Regardless, my question is, how to tweak my expression, such that it covers Case 3, above?

Any and all help appreciated! Thank you!

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I have already reviewed the following threads, but to no avail:

Determine Whether Two Date Ranges Overlap

Determining if two time ranges overlap at any point (Specifically: https://stackoverflow.com/a/13387860/7458905 )

Answer 1

The reason that your last case doesn't return TRUE is due to equality.

You say in case 3:

Let (s1, e1) be defined as (24-JAN-17 07:00, 24-JAN-17 17:00)

Let (s2, e2) be defined as (24-JAN-17 17:00, 25-JAN-17 07:30)

Which means that e1 is equal to s2 (they are both 24-JAN-17 17:00)

But your logic is only true if s2 < e1 , which is NOT true in this case.

Modify your logic so that it returns true if they are equal:

$isOverlapping = (s1 <= e2 && s2 <= e1)

Answer 2

You could use some simple math to do this one, too.

Here we simply break down the components into their unix timestamps and then use the dx/dy of both to determine if they overlap

<?php
function is_overlapping($date_range_1, $date_range_2) {

    // convert into unix timestamp (milliseconds since Jan 1st 1970)
    $d1_1 = make_timestamp($date_range_1[0]);
    $d1_2 = make_timestamp($date_range_1[1]);
    $d2_1 = make_timestamp($date_range_2[0]);
    $d2_2 = make_timestamp($date_range_2[1]);

    // grab the delta of both ranges
    $delta2 = $d2_1 - $d1_2;
    $delta1 = $d2_2 - $d1_1;

    // if either has a delta < 0 then they overlap
    if (($delta2 < 0) || ($delta1 < 0)) { return "true"; }

    // catchall return value
    return "false";
}

// convert to unix timestamp function
function make_timestamp($inp_date) { 
    return strtotime($inp_date);
}

// test cases
print_r("Case 1: " .
        is_overlapping(array("24-JAN-17 07:00", "24-JAN-17 17:00"), 
                       array("24-JAN-17 16:30", "25-JAN-17 17:30"))
       );

print_r("<br>");

print_r("Case 3: " .
        is_overlapping(array("24-JAN-17 07:00", "24-JAN-17 17:00"), 
                       array("24-JAN-17 17:30", "25-JAN-17 18:30"))
       );
?>