面临将文本附加到python中的（file.txt）文件中的问题答案

【问题标题】：Facing problem to append text into a (file.txt) file in python面临将文本附加到python中的（file.txt）文件中的问题
【发布时间】：2020-10-22 08:53:54
【问题描述】：

如何在 python 中将文本附加到 (file.txt) 文件中

这是我的程序代码：

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

aa = 10
bb = 1
cc = 12
xx = 20


try:
    if xx > aa:
        file.write("Yes xx is greater than aa")
        file.close()

    elif xx < aa:
        file.write("No xx is not greater than aa")
        file.close()


    if aa > xx:
        file.write("Yes aa is greater than xx")
        file.close()

    elif aa < xx:
        file.write("No aa is not greater than xx")
        file.close()


    if cc > xx:
        file.write("Yes cc is greater than xx")
        file.close()

    elif cc < xx:
        file.write("No cc is not greater than xx")
        file.close()
except Exception as e:
    print(e)

输出是：

我的问题是为什么只有第一个 if 和 elif 条件起作用并将该字符串写入文本文件，其余条件成功运行但字符串未附加到该文件中。

如果您能告诉我如何解决这个问题，我将不胜感激。

【问题讨论】：

文件在第一次写入后关闭（即条件成功）。
您应该在代码末尾关闭文件。

标签： python python-3.x append file-handling

【解决方案1】：

在向文件写入文本后，您将关闭该文件。如果您关闭该文件，您将无法再写入该文件，除非您再次打开它。如果您使用with-statement，它将为您关闭文件。

试试这样的：

aa = 10
bb = 1
cc = 12
xx = 20

with open("file.txt", "a") as file:
    try:
        if xx > aa:
            file.write("Yes xx is greater than aa")
        elif xx < aa:
            file.write("No xx is not greater than aa")
        if aa > xx:
            file.write("Yes aa is greater than xx")
        elif aa < xx:
            file.write("No aa is not greater than xx")
        if cc > xx:
            file.write("Yes cc is greater than xx")
        elif cc < xx:
            file.write("No cc is not greater than xx")
    except Exception as e:
        print(e)

【讨论】：

【解决方案2】：

您的问题是您正在关闭文件，只要您第一次附加到它。删除file.close() 并最终只使用一次，将解决您的问题。还有一种更 Pythonic 的做事方式，就是使用 with open("file.txt", "a") as file: 这是您的代码的编辑版本：

aa = 10
bb = 1
cc = 12
xx = 20

with open("file.txt", "a") as file:

    try:
        if xx > aa:
            file.write("Yes xx is greater than aa\n")
            
        elif xx < aa:
            file.write("No xx is not greater than aa\n")
            
        if aa > xx:
            file.write("Yes aa is greater than xx\n")
            
        elif aa < xx:
            file.write("No aa is not greater than xx\n")    

        if cc > xx:
            file.write("Yes cc is greater than xx\n")
            
        elif cc < xx:
            file.write("No cc is not greater than xx\n")

        file.close()

    except Exception as e:
        print(e)

P.S \n 是换行符。这样会使输出更整洁。

【讨论】：