PHP isset() Function (original) (raw)

Last Updated : 24 Sep, 2024

The **isset() function in PHP checks whether a variable is declared and not NULL. It returns true if the variable exists and has a non-NULL value, and false otherwise, without modifying the variable.

**Syntax

bool isset( mixed var[,mixedvar [, 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. Below examples illustrate the isset() function in PHP:

**Example 1: In this example we checks if the strvariableissetusingisset().Italsoverifiesifthefirstelementofanemptyarraystr variable is set using isset(). It also verifies if the first element of an empty array strvariableissetusingisset().Italsoverifiesifthefirstelementofanemptyarrayarr is set, printing appropriate messages for both checks.

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Output

Value of variable is set Array is Empty

**Example 2: In this example we use isset() to check if the variable numandspecificelementsinthenum and specific elements in the numandspecificelementsinthearr array are set. It outputs true for existing elements and false for non-existent ones.

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Output

bool(true) bool(true) bool(true) bool(true) bool(false)