03. Datatypes Deep Dive: Mutable vs Immutable & Integer Interning Cache • Python 0-to-Hero Mastery (Big Tech SDE & ML Standard) • Rishabh Ki Kaksha

*   **Immutable (Value change hone par naya memory block banta hai):** `int`, `float`, `str`, `tuple`, `frozenset`, `bool`, `bytes`.
*   **Mutable (In-place modify hote hain, memory address same rehta hai):** `list`, `dict`, `set`, `bytearray`.

---

### 2. Integer Interning Cache (-5 to 256) & String Interning ⚡

CPython performance optimize karne ke liye integers $[-5, 256]$ ko startup par pre-allocate kar leta hai:
```python
a = 256
b = 256
print(a is b) # True (Same memory address in cache!)

x = 257
y = 257
print(x is y) # False in interactive shell (Different memory allocations!)
```

---

### 3. Master Comparison Matrix

| Datatype | Mutable? | Ordered? | Hashable (Can be Dict Key)? |
| :--- | :--- | :--- | :--- |
| **`str` / `int` / `float`**| ❌ No | N/A | 👑 **Yes (Immutable)** |
| **`tuple`** | ❌ No | ✅ Yes | 👑 **Yes (If all elements hashable)** |
| **`list`** | ✅ Yes | ✅ Yes | ❌ No |
| **`dict`** | ✅ Yes | ✅ Yes (Python 3.7+) | ❌ No |
| **`set`** | ✅ Yes | ❌ No | ❌ No |
| **`frozenset`** | ❌ No | ❌ No | 👑 **Yes** |

---

### 4. Interview Ke 3 Sawal Is Topic Se

1. **`is` vs `==` operator me kya fundamental difference hai?** -> `==` value equality check karta hai (`__eq__`); `is` identity (exact memory address `id(a) == id(b)`) check karta hai.
2. **Tuple immutable hone ke bawajood kya uske elements modify ho sakte hain?** -> Haan! Agar tuple ke andar mutable element ho (e.g. `t = (1, [2, 3])`), toh `t[1].append(4)` list ko in-place modify kar dega.
3. **`sys.intern(string)` optimization kab use karni chahiye?** -> NLP ya large dataset dictionary keys me identical strings ke multiple instances ko single shared memory address par point karwane ke liye.

---
**Next Topic:** 04. Dynamic Typing, Duck Typing & Python 3.12 Strict Type Hinting

Loading lesson content...

🎯 Big Tech Coding & Interview Challenges

Practice these curated problems. Click "Load in Sandbox" to solve live in the Code Studio!

1 Questions

Easy

1. Mutability & ID Inspector

Ek function `verify_mutability(val)` likhein jo proof kare ki value mutable hai ya immutable by checking `id()` before and after modification.

💡 View Pro Interview Hint

• id() returns memory memory address

Python 3.12

Full IDE

Live Execution Terminal

Click "Execute Live" to run code.
                

🎯 Big Tech Coding & Interview Challenges

1. Mutability & ID Inspector

Lesson Mastery AI Quiz

AI Doubt Solver

CERTIFICATE OF COMPLETION

Rishabh Gehlot

PHP 8+ & Laravel 11 Master Track