PHP serialize() Function

The isset() function is an inbuilt function in PHP which is used to determine if the variable is declared and its value is not equal to NULL.

Syntax:

bool isset( mixed $var [, mixed $... ] )

Parameters: This function accept one or more parameter as mentioned above and described below:

• $var: It contains the variable which need to check.
• $…: It contains the list of other variables.

Return Value: It returns TRUE if var exists and its value not equal to NULL and FALSE otherwise.