Menene bambanci tsakanin value types da reference types?

Question

Accepted Answer

C# types sun faɗi zuwa nau'uka biyu na ainihi: **value types** (sunayi ajiyar bayanai kai tsaye) da **reference types** (sunayi ajiyar reference/pointer zuwa bayanai a cikin heap). Suna bambanta ta yaya aka ajiya su, aka kwafi su, da aka kwatanta su — bambanci mahimmanci da ke shafar hali a ko'ina cikin harshen.

## Nau'uka biyu

```text
Value types     → struct, int, double, bool, char, enum, DateTime, decimal
                  Stored INLINE (stack for locals); copied BY VALUE.
Reference types → class, string, array, object, interface, delegate
                  Variable holds a REFERENCE to data on the heap; copied BY REFERENCE.
```

## Bambancin mahimmanci: copy semantics

```csharp
// VALUE type — assignment COPIES the value (independent)
int a = 5;
int b = a;      // b is a COPY
b = 10;         // a is still 5

struct Point { public int X; }
Point p1 = new() { X = 1 };
Point p2 = p1;  // COPIES the whole struct
p2.X = 99;      // p1.X is still 1

// REFERENCE type — assignment copies the REFERENCE (both point to the SAME object)
class Box { public int Value; }
Box box1 = new() { Value = 1 };
Box box2 = box1;   // both reference the SAME Box
box2.Value = 99;   // box1.Value is now 99 too!
```

Ajiye value type yana kwafi bayanai (mai zaman kansa); ajiye reference type yana kwafi reference (sunaye biyu sunataka ka'idar jiya ce, don haka canza ta ɗaya yana shafar ɗayan).

## Kwatanta da aika zuwa hanyoyi

```csharp
// == compares VALUES for value types, REFERENCES (identity) for reference types
string s1 = "hi"; // (string is special — == compares content)
Box b1 = new(), b2 = new();
b1 == b2;   // false — different objects (reference equality by default)

// methods get a COPY of value types, the reference (by value) for reference types
void Modify(Box b) { b.Value = 100; }   // affects the caller's object
void Modify(int x) { x = 100; }           // does NOT affect the caller's int
```

## null

```text
Reference types can be null (no object). Value types CANNOT be null
(unless made nullable: int? — a Nullable<int>).
```

## Me yake matukar mahimmanci

Bambancin value-vs-reference shine ɗaya daga cikin ainihin rayuka a C#, kuma yana bayyana jerin hali da kurakurai — don haka ilmin da ya zama dole a sani.
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