> For the complete documentation index, see [llms.txt](https://eastlakeside.gitbook.io/interpy-zh/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://eastlakeside.gitbook.io/interpy-zh/decorators/def_func_in_func.md).

# 在函数中定义函数

刚才那些就是函数的基本知识了。我们来让你的知识更进一步。在 Python 中我们可以在一个函数中定义另一个函数：

```python
def hi(name="yasoob"):
    print("now you are inside the hi() function")

    def greet():
        return "now you are in the greet() function"

    def welcome():
        return "now you are in the welcome() function"

    print(greet())
    print(welcome())
    print("now you are back in the hi() function")

hi()
#output:now you are inside the hi() function
#       now you are in the greet() function
#       now you are in the welcome() function
#       now you are back in the hi() function

# 上面展示了无论何时你调用hi(), greet()和welcome()将会同时被调用。
# 然后greet()和welcome()函数在hi()函数之外是不能访问的，比如：

greet()
#outputs: NameError: name 'greet' is not defined
```

那现在我们知道了可以在函数中定义另外的函数。也就是说：我们可以创建嵌套的函数。现在你需要再多学一点，就是函数也能返回函数。


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