为什么程序中的while循环运行到无穷大

Question

我的python程序应该是一个模拟craigslist论坛帖子，它读取一个包含大量输入的文本文件

filename = input()
myFile = open(filename, "r")
mssgBoard = [["bicycle"], ["microwave"], ["dresser"], ["truck"],["chicken"]]
choice = ""
while (choice != "4"):
    print ("1. Insert an item.")
    print ("2. Search an item.")
    print ("3. Print the message board.")
    print ("4. Quit.")
    choice = myFile.readline()
    if (choice == "1"):
        userInput = ""
        userInput1 = 0
        print ("Enter the item type-b,m,d,t,c: ")
        userInput = myFile.readline()
        print ("Enter the item cost: ")
        userInput1 = myFile.readline()
        if userInput == "b":
            mssgBoard[0].append(userInput1)
        elif userInput == "m":
            mssgBoard[1].append(userInput1)
        elif userInput == "d":
            mssgBoard[2].append(userInput1)
        elif userInput == "t":
            mssgBoard[3].append(userInput1)
        elif userInput == "c":
            mssgBoard[4].append(userInput1)

输入是

1
b
50
1
m
30
3
2
m
40
3
4

Answer 1

您没有从文件中读取的输入中剥离换行符。每行的末尾都有一个隐藏的\n。只需添加.strip()就可以解决这个问题

choice = myFile.readline().strip()