Ans:  Type casting:  converting values from one data type to another is known as type casting.
         Juggling: Automatic conversion is known as type juggling.

sizeof($array) - This function is an alias of count()
count($array) - If you just pass a simple variable instead of an array it will return 1.

1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script - for example,
accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all
- although you can change this default behavior.2. Warnings: These are more serious errors - for example, attempting to include() a file which does not exist.
By default, these errors are displayed to the user, but they do not result in script termination.3. Fatal errors: These are critical errors - for example, instantiating an object of a non-existent class, or calling
a non-existent function. These errors cause the immediate termination of the script, and PHP’s default
behavior is to display them to the user when they take place.

The echo () function is a tad faster because it returns nothing, whereas print() will return 1 if the statement is successfully output.

Casting: Converting values from one data type to another is known as type casting. This is accomplished by placing the intended type in front of the variable to be cast.example:
$x=34.54;
$y=(int)$x;
echo $y; // returns 34Juggling: Variables are sometimes automatically cast to best fit the circumstances in which they are referenced. This is known as Type Juggling.example:
$a="34 items"
$total=5;
$total+=$a;
echo $total;// returns 39