Python购物车程序：调用ordering()后无法触发inside_cart()？

咱们先扒拉一下问题根源：

核心问题1：inside_cart()的循环逻辑直接"自杀"了 #

你看inside_cart()里的while循环最后加了个无条件的break——不管用户选Y还是N，第一次执行完循环体就直接跳出while了，所以哪怕你调用完ordering()，程序也不会再次回到inside_cart()的循环里，直接结束了。

核心问题2：ordering()里的first变量没有全局声明（隐性坑） #

虽然你在全局定义了first = True，但ordering()里用while first==True的时候，没有用global first声明，Python会把它当成局部变量处理，虽然当前代码里你没修改first，但这会埋下隐患，万一之后要修改first的值直接报错。

次要问题：try_again的处理不一致 #

选汉堡（代码1）的时候，try_again没转小写，用户输入大写Y的话会直接跳出，和其他菜品的逻辑不一致，得统一一下。

修复后的完整代码 #

print("(1)Home")
print("- - - - - Welcome to BSITEA - - - - -")
print("\n")
food =["Burger","Fries","Hotdog","Sundae","Coke Float"]
price =[15,10,20,30,50]
cart =[]
cost =[]
counter = 0
first = True

def menu():
    print("- - - - - Menu - - - - -\n")
    collection = [["\nCode","  Description","     Size","   Price"],
                  ["  1","      Burger","      Medium","  15"],
                  ["  2","      Fries","       Medium","  10"],
                  ["  3","      Hotdog","      Medium","  20"],
                  ["  4","      Sundae","      Medium","  30"],
                  ["  5","      Coke Float","  Medium","  50"]]

    for a in collection:
        for b in a:
            print(b,end=' ')
        print()
menu()

def ordering():
    global counter, first  # 声明全局变量
    print("\nPlease select the CODE of the food you want to order")
    while first==True:
        order = input("Type the code you want to order: \n")
        #burger
        if order == ("1"):
            print("You have selected \n")
            print(food[0])
            cart.append(food[0])
            cost.append(price[0])
            counter= counter + 15
            try_again = input("\nWould you like to add more? (Y/N) ").lower()  # 统一转小写
            if try_again != "y":
                break
        #fries
        elif order == ("2"):
            print("You have selected \n")
            print(food[1])
            cart.append(food[1])
            cost.append(price[1])
            counter= counter + 10
            try_again = input("\nWould you like to add more? (Y/N) ").lower()
            if try_again != ("y"):
                break
        #hotdog
        elif order == ("3"):
            print("You have selected \n")
            print(food[2])
            cart.append(food[2])
            cost.append(price[2])
            counter= counter + 20
            try_again = input("\nWould you like to add more? (Y/N) ").lower()
            if try_again != ("y"):
                break
        #sundae
        elif order == ("4"):
            print("You have selected \n")
            print(food[3])
            cart.append(food[3])
            cost.append(price[3])
            counter= counter + 30
            try_again = input("\nWould you like to add more? (Y/N) ").lower()
            if try_again != ("y"):
                break
        #coke float
        elif order == ("5"):
            print("You have selected \n")
            print(food[4])
            cart.append(food[4])
            cost.append(price[4])
            counter= counter + 50
            try_again = input("\nWould you like to add more? (Y/N) ").lower()
            if try_again != ("y"):
                break
        else:
            print("\nInvalid input. Please put only the CODE of the item\n")

def inside_cart():
    global first
    while first == True:
        print(' ')
        print(' ')
        print("The inside of your cart are currently")
        print(cart)
        print(cost)
        print(counter, " Pesos")
    
        suggestion = input("would you like to order more? Y/N: ").lower()
        if suggestion == "y":
            ordering()
        else:
            print("Thank you for ordering!")
            first = False  # 修改first来退出循环，结束程序

ordering()
inside_cart()

修复点说明 #

1. 移除了inside_cart()里的无条件break：改成当用户选N时，把first设为False，这样while循环会自然退出，程序结束；如果选Y，调用ordering()后，回到inside_cart()的循环，继续显示购物车。
2. 给ordering()和inside_cart()加上了global声明：明确使用全局变量，避免局部变量混淆。
3. 统一了try_again的处理逻辑：所有分支都把输入转成小写，不管用户输入Y还是y都能正确识别。
4. 修正了菜单里的"Borgar"拼写错误（强迫症犯了😂）

现在测试一下：选Y继续下单，完成后会回到inside_cart()显示购物车，循环直到你选N退出，完全符合预期效果。

内容的提问来源于stack exchange，提问作者morkie