How to use isset in php

PHP isset() function is used to check whether the variable has been set and assigned a value. Returns true if set, false if not set or null.

Usage of isset() function in PHP

isset() function is used to check whether the variable has been set and is assigned a value. Returns true if the variable has been set, and returns false if the variable has not been set or is null.

Syntax

<code class="php">isset($variable);</code>

Parameters

• $variable: The name of the variable to check

Return value

• Returns true if the variable has been set.
• Returns false if the variable has not been set or is null.

Example

<code class="php"><?php
$name = "John Doe";
$age = null;

if (isset($name)) {
    echo "Name is set and has a value of $name";
}

if (!isset($age)) {
    echo "Age is not set or is null";
}
?></code>

Advantages

• Avoid errors caused by using null values ​​or undefined variables .
• Improve the readability and maintainability of the code.
• Can be used in conjunction with the unset() function to check if a variable is unset.

Note

• isset() only checks whether the variable exists, not its value.
• For object properties, isset() checks whether the property exists in the object.
• For array elements, isset() checks whether the key of the element exists in the array.

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