第七章第4講：python函數的作用域：局部變量與全局變量

1.局部變量：只在函數體內，函數運行之前或運行結束之后，該變量無效

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.全局變量：在主程序（函數外或函數內）到都是生效的

def calculateTax(price,tax_rate):
   print("全局變量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.全局變量在函數體內的修改

def calculateTax(price,tax_rate):
    # print(price)
    my_price=100
    print("全局變量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)

結果：
Enter a price:3
全局變量Myptice: 100
Price =  3 , TotalPrice =  24
Myprice =  3