KwickClips Python · 39 sec · free
How does Python track a function calling itself?
Short answer. Each call adds a frame to the call stack.
Which call returns first?
The last one added.
The call stack
| Call | Waits for | Returns |
|---|---|---|
| fact(3) | 3 * fact(2) | 6 |
| fact(2) | 2 * fact(1) | 2 |
| fact(1) | nothing | 1 |
Remember
| Each call adds a frame |
| Last call returns first |
How does Python track a self call? Calls pile on a stack. Fact of three waits for fact of two. Fact of two waits for fact of one. Fact of one returns, and answers flow back. Each call adds a frame. The last returns first.
This clip is from the full lesson: Recursion in Python — 8 minutes, with the tables, the quick answers and the whole lesson in text.
Useful for: Programming All levels Python, Programming All levels C++
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