Python None
🧩 Python None (Full Guide)
None in Python is a special constant used to represent the absence of a value or nothing.
It is similar to:
| Language | Equivalent |
|---|---|
| JavaScript | null |
| Java | null |
| SQL | NULL |
| PHP | null |
✔️ Type of None
Output:
💡 Only one object of type NoneType exists in Python.
📌 Where is None Used?
1️⃣ Variables with No Value Yet
2️⃣ Default Function Return Value
If a function doesn’t return anything, it returns None.
Output:
3️⃣ Function with Optional Return
4️⃣ To Represent “Nothing Found”
🧠 Checking for None
Use is or is not (not ==).
🚫 Wrong vs Correct
❌ Wrong:
✔ Correct:
🔄 Using None in Conditions
💡 None is False in Boolean Context
Output:
Other values treated as False:
| Value | Boolean Result |
|---|---|
None |
False |
0 |
False |
"" (empty string) |
False |
[] (empty list) |
False |
False |
False |
🧪 Example: Placeholder for Later Assignment
📌 Summary
| Feature | Description |
|---|---|
| Type | NoneType |
| Meaning | No value / empty |
| Boolean Value | False |
| Common Use Cases | Missing data, default values, optional return |
🧠 Practice Tasks
✔ Create a function that returns None if number < 0
✔ Use None as placeholder in variables
✔ Check if a dictionary key exists (return None if not found)
