Python內嵌函數

局部變量

def discount(price, rate):

final_price = price * rate

return final_price

old_price = float(input('請輸入原價：'))    全局變量

rate = float(input('請輸入折扣率：'))

new_price = discount(old_price, rate)

print('打折后的價格是：',new_price)

print('打印局部變量final_price的值：'，final_price) 顯示為定義的變量，final_price為discount函數中的變量，為局部變量，出了discount就無效了  

在局部變量中定義全局變量

>>> test1 = 5

>>> def change():

test1 = 10

print(test1)

>>> change()

10

>>> test1

5

>>> def change():

global test1

test1 = 10

print(test1)

>>> change()

10

>>> test1

10

內嵌函數

>>> def fun1():

print('fun1正在被調用..')

def fun2():

print('fun2正在被調用...')

fun2()

>>> fun1()        調用fun1()后執行調用fun2()

fun1正在被調用..

fun2正在被調用...

閉包 如果在一個內部函數里，對在外部作用域的變量進行引用

>>> def fun3(x):

def fun4(y):

return x * y

return fun4

>>> fun3(1)

<function fun3.<locals>.fun4 at 0x0000000002F549D8>

>>> type(fun3)

<class 'function'>

>>> fun3(1)(2)

2

>>> def fun1():

x = 5

def fun2():

x *= x

return x

return fun2()

>>> fun1()

Traceback (most recent call last):

  File "<pyshell#52>", line 1, in <module>

    fun1()

  File "<pyshell#50>", line 6, in fun1

    return fun2()

  File "<pyshell#50>", line 4, in fun2

    x *= x

UnboundLocalError: local variable 'x' referenced before assignment

>>> def fun1():

x = 5

def fun2():

nonlocal x    強制聲明非局部變量

x *= x

return x

return fun2()

>>> fun1()

25