title: Time difference calculation in milliseconds in php
body: <p>I Have a log reading program written  in PHP. I want to calculate the time difference of any given two log lines.
  I found lot of code for calculating the time difference if the two times are give like</p>
  
  <p>$time1='10:15:30'; and $time2='10:15:35';. here the time difference will be 5 seconds.</p>
  
  <p>But here my input times will be as in the following format
  $time1='10:15:30:300'; and $time2='11:15:35:450';</p>
  
  <p>I want a function which will receive this times as inputs and give the time difference in milliseconds.</p>
  
  <p>Is there any inbuilt php function that can be utilized for this purpose ? or should we write our custom logic to split this time and then calculate the difference ?</p>