C# ni statically typed — variables zina aina inayojulikana wakati wa compile. Unaweza kutangaza variable kwa aina ya wazi au kutumia var kwa type inference (compiler hutambua aina kutoka kwa thamani), lakini kwa njia yoyote aina inabaki imewekwa.
count = ;
name = ;
price = ;
active = ;
age = ;
message = ;
items = List<>();
var hutambua aina kutoka kwa initializer — var age = 30 ni sawa kabisa na int age = 30. Muhimu, var bado ni statically typed: aina imewekwa wakati wa compile (huwezi baadaye kukabidhi string kwa age); inatambuliwa tu, si dynamic.
var x = 5;
x = "hi"; // ❌ compile error — x is an int, can't become a string
var y; // ❌ error — var needs an initializer to infer from
var user = new UserService(); // ✅ type is obvious from the right side — var is clean
var count = users.Count;
int total = CalculateComplexValue(); // explicit when the type isn't obvious aids readability
Tumia var wakati aina iko wazi kutoka upande wa kulia (hupunguza urudufu, hasa na generic types ndefu); tumia explicit types pale inaposaidia uwazi.
const double Pi = 3.14159; // compile-time constant (can't change)
readonly int id; // set once (in constructor), then immutable
int a = 1, b = 2; // multiple of the same type
nint nativeInt; // platform-sized integer
int, long, short, byte integers
float, double, decimal floating point (decimal for money — exact)
bool, char, string boolean, character, text
object the base of all types
Kuelewa kutangaza variable na var ni maarifa ya msingi ya kila siku ya C#.
Hoja kuu ya kidhana ni kwamba var ni type inference, si dynamic typing — kutoelewana kwa kawaida.
Kwa var, compiler hutambua aina kutoka kwa initializer, lakini aina bado imewekwa wakati wa compile (unapata faida zote za static typing — type checking, IntelliSense, performance), bila tu kuandika jina la aina kwa uwazi.
Hii hufanya var iwe urahisi kwa usomekaji (hasa na generic types ndefu kama Dictionary<string, List<int>>) badala ya kulegeza mfumo wa aina.
Kujua wakati wa kutumia var (wakati aina iko wazi kutoka upande wa kulia, kupunguza urudufu) dhidi ya explicit types (pale inaposaidia uwazi), pamoja na built-in types (hasa decimal kwa pesa — arithmetic ya decimal sahihi, tofauti na double), constants (const, readonly), ni maarifa ya kila siku kwa kuandika C#.
Kuelewa kwamba C# ni statically typed kabisa (iwe unaandika aina au unatumia var), na idioms kuhusu kutangaza variable, ni msingi wa kusoma na kuandika C# safi na sahihi, na hoja kwamba var si dynamic ni ufafanuzi wa mara kwa mara unaoonyesha uelewa sahihi wa lugha.