Python Closures Explained: The Function That Remembers

追加: 2026-05-16

[00:00:00]Normally, variables created inside functions disappear after function finishes, but there's one instance where that is not the case. In this video, you're going to learn that example.

[00:00:11]Let's say I have a function called outer, and inside of this function, I have a variable C that has value zero.

[00:00:19]Inside this function, I can create another function, and let's call this one inner function, and this inner function will increase the value of this C variable. But, because I want to use that C variable, I can write non-local.

[00:00:34]This non-local keywords means look in the outer scope for a certain variable.

[00:00:40]And now, when I write C, this will look in this outer function for this C variable. Then, I can write C plus equals one, and then I can return this C variable. After all of this is done, I will return this inner function.

[00:00:57]Now, I will print First, before I print anything, I need to create my count variable, and this count variable will be my outer function. Now, if I call count, do you know what this will print?

[00:01:11]If you know what this will print, do you know what this next count will print? Or the count after that? Write down in the comments below. But, this count will print one, while this count will print two, and this count will print three.

[00:01:26]But, why? The reason is because this inner function now uses non-local C, it means it depends on this outer C. So, this inner function actually remembers the C, even though this outer function call finishes in line nine. In other words, this inner function has memory.

[00:01:47]Such functions that have memory and can remember the variables from the past are called closures. Now, when you run the code, you see I have one, two, and three. If you found this video useful, then you must check my Python course.

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