issubclass() Subclass check
Last updated: 2026-09-22
issubclass() Subclass check
issubclass(cls, classinfo) returns True if cls is a subclass of classinfo.
| Category | Built-in Functions |
|---|---|
| Kind | Built-in Function |
| Python Version | all |
📝 Syntax
issubclass(class, classinfo)⚙️ Parameters
| class Required | The class to check. |
|---|---|
| classinfo Required | A class or tuple of classes; True if class is a subclass. |
Returns：True if class is a subclass of classinfo (or any type in it).
💥 Raises
TypeError— Raised when classinfo is not a class or a tuple of classes.
▶ Example
Edit the code, press Run, and see the result in the output panel:
Output：
True
False🏷️ Related Built-in Functions
💡 Related Cases
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❓ FAQ
QWhat is the difference between issubclass(B, A) and isinstance(b, A)?
Aissubclass compares the inheritance relationship between classes; isinstance compares an instance to a class. For b = B(), isinstance(b, A) returns True.
QWhat does issubclass(A, A) return?
AIt returns True — every class is a subclass of itself.
QWhat happens when the first argument is an instance?
AIt raises a TypeError; issubclass only accepts classes. To check an instance use isinstance.
QHow do I check against several base classes at once?
APass a tuple as the second argument: issubclass(B, (A, C)) returns True if B is a subclass of any of them.
