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finally

Bundan avvalgi darslarimizda try/catch bloki haqida yaxshigina ma’lumotlarni qo’lga kiritigansiz degan umidda ushbu bloklarning finalini ta’minlovchi finally haqida so’z yuritamiz. Dasturlar ba’zida istisno holatlari bilan yakunlangan bo’lishi mumkin, ya’ni dastur tanasining try { … } bloki bajarilmasdan aksincha, dastur catch { … } bloki ichida yakunlangan. Ammo ba’zida dastur xatolik holatiga tushguniga qadar biror yopilishi kerak bo’lgan fayl yoki tarmoqni ochgan bo’lishi mumkin. Bunday ochilgan tarmoq va fayllarni yopish uchun finally { … } blokidan foydalaniladi.

a]:text-periwinkle-700 [&>a:hover]:text-periwinkle-800 [&>code]:bg-periwinkle-700/4 [&>code]:text-inherit [&>code]:shadow-none text-periwinkle-900 fill-periwinkle-700 stroke-periwinkle-700 dark:text-periwinkle-200 dark:[&>a]:text-periwinkle dark:[&>a:hover]:text-periwinkle-600 dark:[&>code]:bg-periwinkle-200/2 dark:[&>code]:text-inherit decoration-periwinkle-700/6 dark:decoration-periwinkle/6 dark:fill-periwinkle-400 dark:stroke-periwinkle-400 flip-heading-hash»>finally bloki har qanday istisno holati (catch) yoki try bloki bajarilishidan qat’iy nazar bajariladi.

«Sizlar nima qilsangiz ham men baribir so’ngida o’z so’zimni aytaman» shiori ostida ish ko’ruvchi blokni amaliy misollarda qaraymiz:

try
{
    int a = 0;
    int b = 5;
    Console.WriteLine(b/a);
}

catch(DivideByZeroException)
{
    Console.WriteLine("0 ga bo'lish mumkin emas !");
}

finally
{
    Console.WriteLine("Dastur ishlashi tugallandi.");
}

Yuqoridagi holatda dasturning istisno holati bajarilgach, finally bloki ichidagi kod o’z ishini boshlaydi. Agar o’zgaruvchilarning qiymatlarini misol uchun a = 2, b = 4 tarzida o’zgartirsak, u holda, dasturning catch bloki bajarilmaydi, lekin so’ngida baribir finally bloki ichidagi kod bajarilishini ko’rish mumkin.

Endi yana bir misolni qaraymiz. Faraz qilaylik, ma’lum katalogdagi fayldagi ma’lumotlarni boshqa faylning ma’lumotlariga qo’shish kerak:

StreamReader reader = null;
StreamWriter writer = null;
try
{
    reader = new StreamReader(File.Open(@"C:UsersPublicDocumentsfile1.txt", FileMode.Open));
    writer = new StreamWriter(File.Open(@"C:UsersPublicDocumentsfile2.txt", FileMode.Append, FileAccess.Write));
    while (reader.Peek() != -1)
    {
        writer.WriteLine(reader.ReadLine());
    }

}

catch(Exception ex)
{
     Console.WriteLine(ex);
}

Yuqoridagi holatda file1.txt faylining ma’lumotlari file2.txt ga qo’shilmoqda. Agar file1.txt dagi ma’lumotlarni o’qishda yoki file2.txt ga ma’lumotlarni yozishda qandaydir xatolik ro’y bersa, dasturning catch bloki bajariladi va xatolik to’g’risida xabar qilinadi. Lekin shuni unutmaslik kerak-ki, dastur catch holatiga tushganda ikkala fayllarning ham holati ochiq holda. Endi ushbu dasturga finally bloki ichida bu ikkala faylni ham yopuvchi kodni yozish eng to’g’ri qaror:

StreamReader reader = null;
StreamWriter writer = null;
try
{
    reader = new StreamReader(File.Open(@"C:UsersPublicDocumentsfile1.txt", FileMode.Open));
    writer = new StreamWriter(File.Open(@"C:UsersPublicDocumentsfile2.txt", FileMode.Append, FileAccess.Write));
    while (reader.Peek() != -1)
    {
        writer.WriteLine(reader.ReadLine());
    }
}

catch(Exception ex)
{
    Console.WriteLine(ex);
}

finally
{
    if(reader != null)
    {
        reader.Close();
    }

    if(writer != null)
    {
        writer.Close();
    }
}

Console.ReadKey();

Dasturlash
finally