How can undefined variable errors be prevented when using $_SESSION in PHP?

When using $_SESSION in PHP, undefined variable errors can be prevented by checking if the session variable is set before trying to access it. This can be done using the isset() function to ensure that the variable exists in the session before using it in your code. 

session_start();

// Check if the session variable is set before accessing it
if(isset($_SESSION['variable_name'])) {
    // Access the session variable safely
    $variable = $_SESSION['variable_name'];
} else {
    // Handle the case where the session variable is not set
    $variable = "default_value";
}

Keywords

$_SESSION error handling isset() session_start() data persistence

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