Question

    items = {'b': 'Bike', 'm': 'Motorcycle', 'd': 'Dresser', 't': 'Trailer', 'c': 'Car',}

while True:
    print "1. Add an item."
    print "2. Find an item."
    print "3. Print the message board."
    print "4. Quit."
    choice = input("Enter your selection: ")
    if choice == 1:
        item = raw_input("Enter the item type-b,m,d,t,c:")
        cost = raw_input("Enter the item cost:")
        elts = []
        elts.append([items[item],cost])
    if choice == 2:
        itemType = raw_input("Enter the item type=b,m,d,t,c:")
        itemCost = raw_input("Enter maximum item cost:")
        if itemType == item and itemCost <= cost:
            print "Sold ", itemType, "for", itemCost
    if choice == 3:
        print str(elts) + ':'
    if choice == 4:
        print elts
        break

我尝试使用添加a来打印str（elts）以分隔它，但是我对此非常新，并且不知道如何以某种方式显示元素。

Answer 1

每次插入项目时，您都会创建一个新列表（elts）。

试试这个：

elts = [] # Create the list here
while True:
    ...
    if choice == 1:
        item = raw_input("Enter the item type-b,m,d,t,c:")
        cost = raw_input("Enter the item cost:")
        # And just append the new element
        # btw, you were appending a list
        # Perhaps this is what you need
        elts.append((items[item], cost)) # Append a tuple
    ...

然后你可以按照自己喜欢的方式处理元组列表：

使用list comprehensions：

if choice == 3:
    print ['{0}:{1}'.format(item, cost) for item, cost in elts]

使用reduce()：

if choice == 3:
    print reduce(lambda t1, t2: '{0}:{1}, {2}:{3}'.format(t1[0], t1[1], t2[0], t2[1]), elts)

<强>更新

你也可以用这个来修复你的第二个条件：

if any([items[itemType] == i and itemCost <= c for i, c in elts]):
    print "Sold ", items[itemType], "for", itemCost

如何以某种方式打印出一组元素？

1 个答案: