Python函数逻辑返回错误的值

这是我的节目。问题是如果我只给出食物值，函数返回错误的部分。但如果我同时给出这两个值，效果就很好了

x = str(input())
y = str(input())

def food(x,y = "Mohakhali"):
    if x == "BBQ Chicken Cheese Burger" and y == "Mohakhali":
        print(250+(250*0.08)+40)
    elif x == "BBQ Chicken Cheese Burger" and y != "Mohakhali":
        print(250+(250*0.08)+60)
    elif x =="Beef Burger" and y =="Mohakhali":
        print(170+(170*0.08)+40)
    elif x =="Beef Burger" and y !="Mohakhali": #for only Beef Burger function prints this.
        print(170+(170*0.08)+60)
    elif x =="Nana Drums" and y =="Mohakhali":
        print(200+(200*0.08)+40)
    elif x =="Nana Drums" and y !="Mohakhali":
        print(200+(200*0.08)+60)
    else:
        print("We dont sell that")
(food(x,y))

---

这是因为当您不为y输入任何值时，它将成为空字符串。虽然它是一个空字符串，但仍将以y=的形式传递给函数

测试：

n [140]: x = str(input())
     ...: y = str(input())
     ...:
     ...: def food(x,y = "Mohakhali"):
     ...:     if x == "BBQ Chicken Cheese Burger" and y == "Mohakhali":
     ...:         print(250+(250*0.08)+40)
     ...:     elif x == "BBQ Chicken Cheese Burger" and y != "Mohakhali":
     ...:         print(250+(250*0.08)+60)
     ...:     elif x =="Beef Burger" and y =="Mohakhali":
     ...:         print(170+(170*0.08)+40)
     ...:     elif x =="Beef Burger" and y !="Mohakhali": #for only Beef Burger function prints this.
     ...:         print(170+(170*0.08)+60)
     ...:     elif x =="Nana Drums" and y =="Mohakhali":
     ...:         print(200+(200*0.08)+40)
     ...:     elif x =="Nana Drums" and y !="Mohakhali":
     ...:         print(200+(200*0.08)+60)
     ...:     else:
     ...:         print("We dont sell that")
     ...:
     ...: if y: food(x,y)
     ...: else: food(x)
     ...:
Beef Burger

223.6

---

您的代码正在按预期工作。你只需要了解它是如何工作的

像foodx一样调用函数。它采用y的默认值，即Mohakhali

输入牛肉汉堡，它将返回223.6

调用foodx，y这样的函数。它接受y的值，即使您没有输入任何与Mohakhali不匹配的内容，因此它将返回下一个条件y！=莫哈卡利

输入牛肉汉堡，然后输入帕拉比或保持空白，它将返回243.6

---

由于您的代码中有两个输入，因此无论您如何调用函数，它总是希望用户使用一个或两个参数提供两个输入。

是的，这是因为您告诉python将Mohakhali的默认值取为变量y，以防未给出。这是问题所在。如果我只给x->牛肉汉堡。我应该得到223.6的值，就像我给y值->Mohakhali一样，但是我得到了243.6。

n [140]: x = str(input())
     ...: y = str(input())
     ...:
     ...: def food(x,y = "Mohakhali"):
     ...:     if x == "BBQ Chicken Cheese Burger" and y == "Mohakhali":
     ...:         print(250+(250*0.08)+40)
     ...:     elif x == "BBQ Chicken Cheese Burger" and y != "Mohakhali":
     ...:         print(250+(250*0.08)+60)
     ...:     elif x =="Beef Burger" and y =="Mohakhali":
     ...:         print(170+(170*0.08)+40)
     ...:     elif x =="Beef Burger" and y !="Mohakhali": #for only Beef Burger function prints this.
     ...:         print(170+(170*0.08)+60)
     ...:     elif x =="Nana Drums" and y =="Mohakhali":
     ...:         print(200+(200*0.08)+40)
     ...:     elif x =="Nana Drums" and y !="Mohakhali":
     ...:         print(200+(200*0.08)+60)
     ...:     else:
     ...:         print("We dont sell that")
     ...:
     ...: if y: food(x,y)
     ...: else: food(x)
     ...:
Beef Burger

223.6