写入以读写模式打开的文件，从而改变结构

Question

我有一个文本文件，其中包含以下内容：

joe satriani is god 
steve vai is god
steve morse is god
steve lukather is god

我想用python编写一个代码，它将更改文件行，例如：

joe satriani is god ,absolutely man ..
steve vai is god,absolutely man ..
steve morse is god,absolutely man ..
steve lukather is god,absolutely man ..

我之前曾经尝试过这样做，但我没有得到预期的结果。所以，首先我尝试编写一个代码，它只会在第一行的末尾附加"绝对人"。

所以，以下是我的代码：

jj = open('readwrite.txt', 'r+')
jj.seek(1)
n = jj.read()
print(" yiuiuiuoioio n") #just for debugging
print(n)
f = n.split("n" , n.count("n")) #to see what I am getting
print(f)   #As it turns out read returns the whole content as a string
print(len(f[0])) # just for debugging
jj.seek(len(f[0])) #take it to the end of first line
posy = jj.tell() # to see if it actually takes it 
print(posy)
jj.write(" Absolutely ..man ")

但是在执行代码时，我的文件更改为以下内容：

joe satriani is god Absolutely ..man d
steve morse is god
steve lukather is god

第二行被覆盖。如何在一行末尾附加到一个字符串？

我想过以读取和附加模式打开文件，但它会覆盖现有文件。我不想从这个文件中读取字符串并通过附加将其写入另一个文件。如何附加或更改文件的行？

有什么方法可以在没有任何软件包的情况下做到这一点吗？

Answer 1

如果要写入同一文件，这是解决方案

file_lines = []
with open('test.txt', 'r') as file:
for line in file.read().split('n'):
file_lines.append(line+ ", absolutely man ..")
with open('test.txt', 'w') as file:
for i in file_lines:
file.write(i+'n')

如果您想写入其他文件，这是解决方案

with open('test.txt', 'r') as file:
for line in file.read().split('n'):
with open('test2.txt', 'a') as second_file:
second_file.write(line+ ", absolutely man ..n")

Answer 2

given_str = 'absolutely man ..'
text = ''.join([x[:-1]+given_str+x[-1] for x in open('file.txt')])
with open('file.txt', 'w') as file:
file.write(text)

Answer 3

尝试用 seek 写一些东西。 您只是重写而不是插入，因此您必须在编写文本后复制文件的末尾

jj = open('readwrite.txt', 'r+')
data = jj.read()
r_ptr = 0
w_ptr = 0
append_text = " Absolutely ..man n"
len_append = len(append_text)
for line in data.split("n"): #to see what I am getting
r_ptr += len(line)+1
w_ptr += len(line)
jj.seek(w_ptr)
jj.write(append_text+data[r_ptr:])
w_ptr += len_append