How can undefined variable and index errors be avoided in PHP scripts?

To avoid undefined variable and index errors in PHP scripts, it is important to check if a variable or array index exists before trying to access it. This can be done using isset() function to determine if a variable is set and not null, and array_key_exists() function to check if a specific key exists in an array. 

// Check if a variable is set before using it
if(isset($variable)){
    // Do something with $variable
}

// Check if a key exists in an array before accessing it
$array = array('key1' => 'value1', 'key2' => 'value2');
if(array_key_exists('key1', $array)){
    // Access $array['key1']
}

Keywords

error handling isset function array_key_exists function strict typing debugging

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