Python如何在不删除已有内容的情况下继续写入文件

Question

在 Windows 中编写我的 python 3.3 程序时，我遇到了一个小问题。我正在尝试将一些指令行写入文件以供程序执行。但是每次我 file.write() 下一行时，它都会替换上一行。我希望能够尽可能多地向该文件写入行。注意:使用“\n”似乎不起作用，因为您不知道会有多少行。请帮忙!这是我的代码(作为一个循环，我确实运行了多次):

menu = 0
while menu != None:
    menu = lipgui.choicebox("Select an option:", choices=["choice1", "choice2", "choice3"])
    file = open("file.txt", "w")
    if menu == "choice1":
       text_to_write = lipgui.enterbox("Text to write:")
       file.write(text_to_write)

Answer 1

每次打开文件进行写入时，它都会被删除(截断)。改为打开文件进行追加，或者只打开文件一次并保持打开状态。

要打开文件进行追加，请使用 a 而不是 w 作为模式:

while menu != None:
    menu = lipgui.choicebox("Select an option:", choices=["choice1", "choice2", "choice3"])
    file = open("file.txt", "a")
    if menu == "choice1":
       text_to_write = lipgui.enterbox("Text to write:")
       file.write(text_to_write)

或者在循环外打开文件:

file = open("file.txt", "w")

while menu != None:
    menu = lipgui.choicebox("Select an option:", choices=["choice1", "choice2", "choice3"])
    if menu == "choice1":
       text_to_write = lipgui.enterbox("Text to write:")
       file.write(text_to_write)

或仅在您第一次需要时使用一次:

file = None

while menu != None:
    menu = lipgui.choicebox("Select an option:", choices=["choice1", "choice2", "choice3"])
    if file is None:
        file = open("file.txt", "w")
    if menu == "choice1":
       text_to_write = lipgui.enterbox("Text to write:")
       file.write(text_to_write)