Answer 1

Because when you put true at the end of the statement it becomes a case-insensitive Name being (MSG) No matter how you call it!...( MSG, msg, Msg, mSg, msG, MsG, MSg, mSG) ^_^ All of these will return the 'String' ....Because the Name (MSG) YOU HAVE DEFINED TOO BE CASE-INSENSITIVE SO WHETHER YOU CALL IT WITH ECHO USING LOWER CASE OR UPPER CASE IT WILL STILL BE CALLED! ^_^ IF YOU DONT PUT TRUE IT HAS TO BE TYPED THE EXACT SAME WAY THE NAME IS DEFINED SO IN THIS CASE IF YOU REMOVE TRUE IT WILL NOT WORK UNLESS YOU EDIT THE LOWER CASE (echo msg) too (echo MSG) ALL CAPS BECAUSE THATS HOW IT WAS DEFINED

<?php
define("MSG", " Hi SoloLearners!", true);
echo msg;
?>

https://code.sololearn.com/wiigGPnSceky/?ref=app

https://code.sololearn.com/wL7W7Eo2CQXz/?ref=app