每次运行脚本python时将用户输入保存到现有文本文件？

Question

I'm trying to save the user input into one text file(I want to keep the record for a month).

But I'm not sure how to keep the old user input because every time I re-run the script new user input is automatically written on old-user input.

Is there any way to keep all the records regardless of running the script?

This is a simple example.

When I run the script once, I get the following result in output textile,

2.5 2015-07-30
7   2015-07-30
1   2015-07-30
4   2015-07-30
5   2015-07-30
8.9 2015-07-30

but when I re-run the script, the above data is all being written by new user input. How can I make it so that my output text file maintains all the record regardless of running the script? This is my desired look of my output text file

2.5 2015-07-30
7   2015-07-30
1   2015-07-30
4   2015-07-30
5   2015-07-30
8.9 2015-07-30
4   2015-07-31
7   2015-07-31
2.4 2015-07-31
5   2015-07-31
1   2015-07-31

and this is the code that I've tried so far.

import datetime

with open("output.txt", 'w') as textfile:
    while True:
        input = raw_input("Enter: ")
        if input == 'done':
            break
        textfile.write(input+'\t'+ datetime.datetime.now().strftime("20%y-%m-%d")+'\n')

Answer 1

You need to open the file in append mode to preserve the data already in the file.

'a' opens the file for appending.

'a+' opens the file for appending and creates the file if it does not exist.

import datetime

with open("output.txt", 'a+') as textfile:
    while True:
        input = raw_input("Enter: ")
        if input == 'done':
            break
        textfile.write(input+'\t'+ datetime.datetime.now().strftime("20%y-%m-%d")+'\n')