How to append new data onto a new line

问题:

My code looks like this:

def storescores():

   hs = open("hst.txt","a")
   hs.write(name)
   hs.close() 

so if I run it and enter "Ryan" then run it again and enter "Bob" the file hst.txt looks like

RyanBob 

instead of

Ryan
Bob

How do I fix this?

回答1:

If you want a newline, you have to write one explicitly. The usual way is like this:

hs.write(name + "\n")

This uses a backslash escape, \n, which Python converts to a newline character in string literals. It just concatenates your string, name, and that newline character into a bigger string, which gets written to the file.

It's also possible to use a multi-line string literal instead, which looks like this:

"""
"""

Or, you may want to use string formatting instead of concatenation:

hs.write("{}\n".format(name))

All of this is explained in the Input and Output chapter in the tutorial.

回答2:

All answers seem to work fine. If you need to do this many times, be aware that writing

hs.write(name + "\n")

constructs a new string in memory and appends that to the file.

More efficient would be

hs.write(name)
hs.write("\n")

which does not create a new string, just appends to the file.

回答3:

I had the same issue. And I was able to solve it by using a formatter.

file_name = "abc.txt"
new_string = "I am a new string."
opened_file = open(file_name, 'a')
opened_file.write("%r\n" %new_string)
opened_file.close()

I hope this helps.

回答4:

There is also one fact that you have to consider. You should first check if your file is empty before adding anything to it. Because if your file is empty then I don't think you would like to add a blank new line in the beginning of the file. This code

1. first checks if the file is empty
2. If the file is empty then it will simply add your input text to the file else it will add a new line and then it will add your text to the file. You should use a try catch for os.path.getsize() to catch any exceptions.

Code:

import os

def storescores():
hs = open("hst.txt","a")
if(os.path.getsize("hst.txt") > 0):
   hs.write("\n"+name)
else:
   hs.write(name)

hs.close()

回答5:

In Python >= 3.6 you can use new string literal feature:

with open('hst.txt', 'a') as fd:
    fd.write(f'\n{name}')

Please notice using 'with statment' will automatically close file when it fd runs out of scope

回答6:

I presume that all you are wanting is simple string concatenation:

def storescores():

   hs = open("hst.txt","a")
   hs.write(name + " ")
   hs.close() 

Alternatively, change the " " to "\n" for a newline.

回答7:

The answer is not to add a newline after writing your string. That may solve a different problem. What you are asking is how to add a newline before you start appending your string. If you want to add a newline, but only if one does not already exist, you need to find out first, by reading the file.

For example,

with open('hst.txt') as fobj:
    text = fobj.read()

name = 'Bob'

with open('hst.txt', 'a') as fobj:
    if not text.endswith('\n'):
        fobj.write('\n')
    fobj.write(name)

You might want to add the newline after name, or you may not, but in any case, it isn't the answer to your question.