What are the best practices for handling array keys in PHP to prevent errors like "Notice: Use of undefined constant"?

When working with array keys in PHP, it is important to ensure that the keys are defined before using them to prevent errors like "Notice: Use of undefined constant". One way to avoid this issue is to check if the key exists using the `isset()` function before accessing it. 

// Check if the key exists before using it
if(isset($array['key'])){
    // Access the key if it exists
    $value = $array['key'];
    // Use the value as needed
} else {
    // Handle the case where the key is not defined
    echo "Key 'key' is not defined in the array.";
}

Keywords

array keys PHP error handling undefined constant notice error

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