C# mbedakake tipe-tipe sing bisa saka sing ora bisa. () ngaweake tipe nilai bisa nampung null, (fitur compiler) mbantu tangkep bug null, lan (, , ) ndadekake karya karo nilai sing mungkin-null resik lan aman — ngatasi masalah referensi-null sing umum.
nullint??.??!int x = 5; // a value type — CANNOT be null
int? y = null; // int? = Nullable<int> — CAN be null
if (y.HasValue) { int val = y.Value; } // check + access
int z = y ?? 0; // default if null
Tipe nilai ora bisa normal dadi null, nanging int? (Nullable<int>) ngaweake iku — umum kanggo data opsional/ilang (cth. kolom database nullable).
#nullable enable // (on by default in modern projects)
string name = null; // ⚠️ warning — string is non-nullable by default now
string? maybe = null; // ✅ string? explicitly allows null
void Use(string? s) {
Console.WriteLine(s.Length); // ⚠️ warning — s might be null (must check first)
}
Karo tipe referensi nullable diaktifake, compiler nglacak referensi mana bisa null (string?) vs ora (string) lan paring prentah nalika sampeyan mungkin dereference null — tangkep NullReferenceException bug ing wektu compile. Iki minangka fitur kamingan C# modern utama.
// ?. null-conditional — short-circuits to null instead of throwing
int? len = user?.Name?.Length; // null if user or Name is null (no exception)
user?.DoSomething(); // only calls if user isn't null
// ?? null-coalescing — provide a default
string name = input ?? "Anonymous";
name ??= "fallback"; // assign if currently null
// ! null-forgiving — assert non-null (suppress the warning; use carefully)
string definitelyNotNull = maybe!; // "I know it's not null" — no runtime check
Operator null-conditional (?.) ngakses anggota nilai sing mungkin-null kanthi aman (bali null tinimbang mula), lan ?? nyedhiyakake pamunas standar — babar gayeng ndadekake nangani null resik lan aman.
Nangani null minangka salah siji aspek paling penting ing nulis C# sing robus, amarga NullReferenceException ("kesalahan setelusan dolar") minangka salah siji kesalahan runtime paling umum — lan fitur tipe nullable lan operator C# langsung ngatasi iku, ndadekake kaone pengetahuan penting. Tipe nilai nullable (int?) praktis perlu kanggo nggambarake data opsional/ilang (kolom database nullable, nilai opsional).
Fitur tipe referensi nullable (saiki aktif-standar ing proyek .NET modern) minangka peningkatan kamingan utama: kanthi compiler nglacak lan paring prentah bab dereference null sing mungkin, iku tangkep kelas lengkap bug null ing wektu compile tinimbang minangka jatuh runtime — kauntungan reliabilitas signifikan sing kudu sampeyan mengerti lan turuti.
Operator nangani null minangka alat saben-dina sing ndadekake karya karo nilai sing mungkin-null resik lan aman: operator null-conditional (?.) kanthi aman navigasi rantai sing mungkin-null (bali null tinimbang mula), ??/??= nyedhiyakake pamunas kanthi ringkas, lan ! payo non-null (digunakake kanthi ati-ati).
Mengerti tipe nilai nullable, fitur kamingan tipe-referensi-nullable, lan operator nangani null (?., ??, !) penting kanggo nulis C# sing aman-null, robus sing matiya-malahi NullReferenceException — keprihatinan sering, praktis-kritis.
Amarga bug sing gegandhengan null umum banget lan C# nyedhiyakake alat kuwat (utamane pengecekan null wektu compile) kanggo matiya-malahi iku, ngrengrengi tipe nullable lan operator null minangka pengetahuan fondasi, kudu-ngerti kanggo nulis C# modern sing reliabel.