What are common pitfalls when accessing variables within functions in PHP?

Common pitfalls when accessing variables within functions in PHP include variable scope issues, where variables defined outside of a function are not accessible inside the function, and variable shadowing, where a variable with the same name as an external variable is created inside the function, leading to unexpected behavior. To solve these issues, you can use the global keyword to access external variables within a function, or pass variables as arguments to the function to avoid shadowing.

// Variable scope issue
$externalVar = 10;

function accessExternalVar(){
    global $externalVar;
    echo $externalVar;
}

accessExternalVar(); // Output: 10

// Variable shadowing issue
$var = 5;

function shadowingExample($var){
    echo $var;
}

shadowingExample($var); // Output: 5