我为什么无法隐式地将浮点数转换为字符串？

Question

运行这个有点麻烦。基本上，我只想得到一个数额，如果它超过50免费送货和少于10美元额外收费。我一直收到一个关于将浮点转换为str隐式的错误？我认为我的输入应该被视为浮动？在

#declare flags
shippingCharge = 10
freeShipping = False
#Get number and convert to float?
purchaseAmount = float(input("\nHow much is the purchase amount? "))

if (purchaseAmount) >= 50 : 
    freeShipping = True
    print("Your purchase amount is " + purchaseAmount + "$ and shipping is free!")
else : 
    print("Your purchase amount is " + purchaseAmount + "$ and shipping is " + shippingCharge + "$.")
    purchaseAmount = shippingCharge + purchaseAmount
    print("Your new total is " + purchaseAmount)
print ("Have a nice day and thank you for shopping with us.")

Answer 1

问题在于你的书面陈述：

print("Your purchase amount is " + purchaseAmount + "$ and shipping is free!")

如果要在不进行转换的情况下连接字符串和浮点，请尝试向变量添加str（）强制转换：

即：

^{pr2}$

也可以使用格式：

print("Your purchase amount is {0}$ and shipping is free!".format(purchaseAmount))

Answer 2

因为Python是一种强类型语言：

https://wiki.python.org/moin/Why%20is%20Python%20a%20dynamic%20language%20and%20also%20a%20strongly%20typed%20language

您需要显式地将类型转换为string。它不会自动为你故意这么做。在

Answer 3

只需将purchaseAmount替换为str（purchaseAmount），就可以了。在

How much is the purchase amount? 50
Your purchase amount is 50.0$ and shipping is free!
Have a nice day and thank you for shopping with us.