Python零基础学习者求助：Codecademy项目中TypeError错误解析

嘿，别慌！这个错误其实是个超容易踩的语法小坑，我来给你掰扯清楚～

错误原因分析 #

你看到的TypeError: bad operand type for unary +: 'str'，问题全出在你写的=+上！

在Python里，正确的加法赋值运算符是+=，而你写的=+会被Python拆解成两部分：

• 首先是一元运算符+（用来给数值取正）
• 然后是赋值运算符=

但你这里右边的是字符串（比如lovely_loveseat_description），字符串根本不支持一元+操作，所以Python直接抛出了错误。而且不止第17行，你代码里所有的customer_one_total =+ ...和customer_one_itemization =+ ...都是同样的问题。

修正后的代码 #

把所有的=+改成+=就搞定了，修正后的代码如下：

lovely_loveseat_description = """Lovely Loveseat. Tufted polyester blend on wood. 32 inches high X 40 inches wide X 30 inches deep. Available in Red or White."""
lovely_loveseat_price = 254.00
stylish_settee_description = """Stylish Settee. Faux leather on birch. 29.50 inches high X 54.75 inches wide X 28 inches deep. Available only in Black."""
stylish_settee_price = 150.50
luxurious_lamp_description = "Luxurious Lamp. Glass and iron. 36 inches tall. Available in Brown with a Stylish Beige shade."
luxurious_lamp_price = 52.15
#sales tax variable.
sales_tax = .088
#base shopping cart total value.
customer_one_total = 0
#shopping cart contents variable.
customer_one_itemization = ""
#shopping area.
customer_one_total += lovely_loveseat_price
customer_one_itemization += lovely_loveseat_description
customer_one_total += luxurious_lamp_price
customer_one_itemization += luxurious_lamp_description
customer_one_tax = customer_one_total * sales_tax
customer_one_total += customer_one_tax
print("Customer One Items:")
print(customer_one_itemization)
print("Customer One Total Cost:")
print(customer_one_total)

额外小提示 #

如果想让输出的总价更美观（保留两位小数，符合货币格式），可以把最后一行打印代码改成：

print(f"Customer One Total Cost: ${customer_one_total:.2f}")

这样会输出更友好的Customer One Total Cost: $333.09。

内容的提问来源于stack exchange，提问作者Tyler Wishart