为什么这个 Python 代码不能将一个文件中的文本复制到另一个文件中？

Question

所以，我正在尝试将一些文本从一个 .txt 文件复制到另一个文件。但是，当我打开第二个 .txt 文件时，程序并没有在其中写入这些行。这是我正在使用的代码。

chptfile = open('v1.txt',"a+",encoding="utf-8")
chptfile.truncate(0)
chptfile.write("nee\n")
chptfile.write("een")

lines = chptfile.readlines()
chptv2 = open ('v2.txt',"a+",encoding="utf-8")
for line in lines:
    chptv2.write(line)

chptv2.close()
chptfile.close()

Answer 1

写完后chptfile的文件指针在文件末尾，需要调用seek方法将文件指针移回文件开头在您阅读其内容之前：

chptfile = open('v1.txt',"a+",encoding="utf-8")
chptfile.truncate(0)
chptfile.write("nee\n")
chptfile.write("een")
chptfile.seek(0)
lines = chptfile.readlines()
...

Answer 2

就像 blhsing 的回答一样，您需要调用 seek() method. However, there is also a bad practice in you code. Instead of opening and closing a file, use a context manager:

with open('v1.txt',"a+",encoding="utf-8") as chptfile:
    chptfile.truncate(0)
    chptfile.write("nee\n")
    chptfile.write("een")
    chptfile.seek(0)
    lines = chptfile.readlines()

with open ('v2.txt',"a+",encoding="utf-8") as chptv2:
    chptv2.write(''.join(line))

为什么这个 Python 代码不能将一个文件中的文本复制到另一个文件中？

Why isn't this Python code copying the text in one file to another?

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text-files