第七章第4讲：python函数的作用域：局部变量与全局变量

1.局部变量：只在函数体内，函数运行之前或运行结束之后，该变量无效

def calculateTax(price,tax_rate):
    print(price)
    taxTotal = price * tax_rate
    return taxTotal

my_price = int(input("Enter a price:"))
totalPrice = calculateTax(my_price,8)
print("Price = ",my_price,",","TotalPrice = ",totalPrice)
# print(price)

 2.全局变量：在主程序（函数外或函数内）到都是生效的

def calculateTax(price,tax_rate):
   print("全局变量Myptice:", my_price)
    taxTotal = price * tax_rate
    return taxTotal

my_price = int(input("Enter a price:"))
totalPrice = calculateTax(my_price,8)
print("Price = ",my_price,",","TotalPrice = ",totalPrice)
print("Myprice = ",my_price)

 3.全局变量在函数体内的修改

def calculateTax(price,tax_rate):
    # print(price)
    my_price=100
    print("全局变量Myptice:", my_price)
    taxTotal = price * tax_rate
    return taxTotal

my_price = int(input("Enter a price:"))
totalPrice = calculateTax(my_price,8)
print("Price = ",my_price,",","TotalPrice = ",totalPrice)
print("Myprice = ",my_price)

结果：
Enter a price:3
全局变量Myptice: 100
Price =  3 , TotalPrice =  24
Myprice =  3