تجنب NullReferenceException في C#

To avoid NullReferenceException (NRE) when reading the tag of a button in C#, you can make a few adjustments to your code. First, ensure that you are only iterating over buttons by checking the type of each control. Secondly, check if the Tag property is null before calling ToString() on it. Here’s an updated version of your code:

csharpCopy code
// Create a list to store the seat buttons
List seatbuttons = new List();

// Iterate over all controls on the form
foreach (Control control in this.Controls)
{
    // Check if the control is a button
    if (control is Button seatbutton)
    {
        // Check if the Tag property is not null
        if (seatbutton.Tag != null)
        {
            // Add the button to the list if the Tag is not empty
            string betta = seatbutton.Tag.ToString();
            if (!string.IsNullOrEmpty(betta))
            {
                seatbuttons.Add(seatbutton);
            }
        }
    }
}

In this updated code, we first check if the control is a button using the is keyword and then cast it to a Button in the same line using a pattern matching syntax (Button seatbutton). This way, we ensure that only buttons are processed. Then, we check if the Tag property is not null before attempting to convert it to a string to avoid the NRE.

Regarding good coding habits, here are some tips:

1. Null checking: Always check for null before accessing properties or methods of an object to avoid NREs.

2. Type checking: Use type checking (e.g., is keyword) to ensure that you are working with the correct types.

3. Error handling: Use try-catch blocks for exceptional cases, but avoid using them for regular flow control.

4. Consistent naming: Use meaningful and consistent names for variables, methods, and classes to improve code readability.

5. Code readability: Write code that is easy to read and understand. Use comments to explain complex logic or intent.

6. Code organization: Organize your code into logical units (e.g., classes, methods) to improve maintainability and reusability.

7. Testing: Write unit tests to ensure that your code behaves as expected, especially when handling edge cases like null values.

تأكد أنك تستخدم مبدأ تصميم البرمجيات SOLID ومبادئ البرمجة النظيفة (Clean Code) لتحسين جودة وصيانة الكود. قم بتجنب استخدام الـ try-catch للتحكم في التدفق الطبيعي للبرنامج، واستخدمها فقط للتعامل مع حالات الخطأ الفعلية.

كما يُفضل استخدام النمط الحلقي (Iterative pattern) بدلاً من النمط التجريبي (Trial pattern) للحصول على النتائج المرجوة بشكل أكثر فعالية وفعالية. كما يمكنك استخدام LINQ لتبسيط الكود وجعله أكثر قراءة وصيانة.