Python如何在不删除文件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。我希望能够继续向该文件写入尽可能多的行。注意：使用 "\n" 似乎不起作用，因为您不知道将有多少行。请帮忙！这是我的代码（作为一个循环，我确实多次运行）：

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，它都会被擦除（截断）。打开文件进行追加，或者只打开一次文件并保持打开状态。

要打开文件进行追加，请使用a代替w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)