Fixing the "Trying to access array offset on value of type null" Error

The error "Trying to access array offset on value of type null" occurs when you attempt to access an array key that does not exist or is set to null. This commonly happens when fetching data from a database and there are no matching records.

Solution:

To resolve this error, it is essential to check for the truthiness of the value or the existence of the key you wish to access. Here are a few ways to do this:

1. Check for Truthiness:

You can use the truth check operator (&&) to ensure that the array element exists and has a value.

if ($m11to1 && $m11to1["lecture_day"] == !'') {
    echo "" . $m11to1["lecture_name"] . "";
} else {
    echo "no class";
}

2. Use Default Values:

If you need a specific value from the result array, you can specify a default value if the result is not present.

$lecture = $m11to1["lecture_day"] ?? 'not found';

3. PDO Implementation:

For PDO, you can check the value similarly:

$lecture = $m11to1["lecture_day"] ?? null;

By implementing these techniques, you can avoid the "Trying to access array offset on value of type null" error and ensure that your code gracefully handles missing or null values.