你可以在需要这种行为的特定地方装饰方法write:

#Changed behavior is localized to single place.
with open('test1.txt', 'w') as file:    
    def decorate_with_new_line(method):
        def decorated(text):
            method(f'{text}\n')
        return decorated
    file.write = decorate_with_new_line(file.write)
    
    file.write('This will be on line 1')
    file.write('This will be on line 2')
    file.write('This will be on line 3')

#Standard behavior is not affected. No class was modified.
with open('test2.txt', 'w') as file:
        
    file.write('This will be on line 1')
    file.write('This will be on line 1')
    file.write('This will be on line 1')  

你可以通过两种方式做到这一点:

f.write("text to write\n")

或者，取决于你的Python版本(2或3):

print >>f, "text to write"         # Python 2.x
print("text to write", file=f)     # Python 3.x

如果你大量使用它(写了很多行)，你可以子类化'file':

class cfile(file):
    #subclass file to have a more convienient use of writeline
    def __init__(self, name, mode = 'r'):
        self = file.__init__(self, name, mode)

    def wl(self, string):
        self.writelines(string + '\n')

现在它提供了一个额外的函数wl来做你想要的:

with cfile('filename.txt', 'w') as fid:
    fid.wl('appends newline charachter')
    fid.wl('is written on a new line')

也许我遗漏了一些东西，比如不同的换行符(\n， \r，…)，或者最后一行也以换行符结束，但这对我来说是有效的。

你可以这样做:

file.write(your_string + '\n')

正如另一个答案所建议的，但为什么在可以调用文件时使用字符串连接(缓慢，容易出错)。写两次:

file.write(your_string)
file.write("\n")

注意，写操作是被缓冲的，所以两者是一样的。

另一个解决方案是使用fstring从列表中写入

lines = ['hello','world']
with open('filename.txt', "w") as fhandle:
  for line in lines:
    fhandle.write(f'{line}\n')

作为一个函数

def write_list(fname, lines):
    with open(fname, "w") as fhandle:
      for line in lines:
        fhandle.write(f'{line}\n')

write_list('filename.txt', ['hello','world'])

这是我自己想出来的解决方法为了系统地产生n作为分离器。它使用一个字符串列表，其中每个字符串是文件的一行，但它似乎也可以为您工作。(Python 3 +)。

#Takes a list of strings and prints it to a file.
def writeFile(file, strList):
    line = 0
    lines = []
    while line < len(strList):
        lines.append(cheekyNew(line) + strList[line])
        line += 1
    file = open(file, "w")
    file.writelines(lines)
    file.close()

#Returns "\n" if the int entered isn't zero, otherwise "".
def cheekyNew(line):
    if line != 0:
        return "\n"
    return ""