Are there any best practices or coding conventions to follow to avoid the mentioned warning in PHP?

The warning "Undefined index" in PHP occurs when trying to access an array key that does not exist. To avoid this warning, it is recommended to check if the key exists before accessing it using isset() or array_key_exists() functions. 

// Check if the key exists before accessing it
if (isset($array['key'])) {
    // Access the key if it exists
    $value = $array['key'];
} else {
    // Handle the case when the key does not exist
    $value = null;
}

Keywords

PHP coding conventions warning error handling best practices

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