There is a very basic difference between undeclared and undefined variable
Undefined Variable are those which are present in program but they haven’t assign any value or if the value assigned to the variable is undefined.
While on the other hand undeclared variable are those which do not exist in the program and if the program tries to read that undeclared then a run time error is thrown.
Stay tuned for the PHP Magento, WordPress, JavaScript and Magento2 latest tutorial and updates, Hope you enjoyed reading, if you need the professional Magento Development / PHP we can help you, just Click on the Link and send me your requirements.
Please Like the Post on Facebook or Google+.