写入多行文件，然后使用Python读取它们

Question

I've just undertaken my first proper project with Python, a code snippet storing program. To do this I need to first write, then read, multiple lines to a .txt file. I've done quite a bit of googling and found a few things about writing to the file (which didn't really work). What I have currently got working is a function that reads each line of a multiline input and writes it into a list before writing it into a file. I had thought that I would just be able to read that from the text file and add each line into a list then print each line separately using a while loop, which unfortunately didn't work. After going and doing more research I decided to ask here. This is the code I have currently:

'''
Project created to store useful code snippets, prehaps one day it will evolve
into something goregous, but, for now it's just a simple archiver/library
'''

#!/usr/local/bin/python

import sys, os, curses

os.system("clear")

Menu ="""
                #----------- Main Menu ---------#

                #   1. Create or edit a snippet #
                #   2. Read a snippet           # 
                #   0. Quit                     #

                #-------------------------------#
\n
"""

CreateMenu ="""
        #-------------- Creation and deletion --------------#

        #   1. Create a snippet                             #
        #   2. Edit a snippet                               # 
        #   3. Delete a snippet (Will ask for validation)   #
        #   0. Go back                                      #           

        #---------------------------------------------------#
\n
"""

ReadMenu="""
                  #------ Read a snippet ------#

                  #   1. Enter Snippet name    #
                  #   2. List alphabetically   #
                  #   3. Extra                 #
                  #   0. Go Back               #

                  #----------------------------#

"""

def readFileLoop(usrChoice, directory):
    count = 0

    if usrChoice == 'y' or 'n':
        if usrChoice == 'y':
            f = open(directory, 'r')
            text = f.read()
            f.close() 

            length = len(text)
            print text
            print length

            raw_input('Enter to continue')
            readMenu()
            f.close()
        elif choice == 'n':
            readMenu()



def raw_lines(prompt=''):
   result = []
   getmore = True
   while getmore:
      line = raw_input(prompt)
      if len(line) > 0:
         result.append(line)
      else:
         getmore = False
   result = str(result)
   result.replace('[','').replace(']','')
   return result


def mainMenu():
    os.system("clear")
    print Menu
    choice = ''
    choice = raw_input('--: ')
    createLoop = True    

    if choice == '1':
            return creationMenu()

    elif choice == '2':
        readMenu()

    elif choice == '0':
        os.system("clear")
        sys.exit(0)

def create():
        os.system("clear")
        name = raw_input("Enter the file name: ")
        dire = ('shelf/'+name+'.txt')

        if os.path.exists(dire):
            while os.path.exists(dire):
                os.system("clear")
                print("This snippet already exists")
                name = raw_input("Enter a different name: ")
                dire = ('shelf/'+name+'.txt')

            print("File created\n")
            f = open(dire, "w")
            print("---------Paste code below---------\n")
            text = raw_lines()
            raw_input('\nEnter to write to file')
            f.writelines(text)
            f.close()
            raw_input('\nSnippet successfully filled, enter to continue')


        else:
            print("File created")
            f = open(dire, "w")
            print("---------Paste code below---------\n")
            text = raw_lines()
            print text
            raw_input('\nEnter to write to file')
            f.writelines(text)
            f.close()
            raw_input('\nSnippet successfully filled, enter to continue')

def readMenu():
    os.system("clear")

    name = ''
    dire = ''

    print ReadMenu 
    choice = raw_input('--:') 

    if choice == '1':
        os.system("clear")
        name = raw_input ('Enter Snippet name: ')
        dire = ('shelf/'+name+'.txt')

        if os.path.exists(dire):
            choice = ''
            choice = raw_input('The Snippet exists! Open? (y/n)')

            '''if not choice == 'y' or 'n':
                while (choice != 'y') or (choice != 'n'):
                    choice = raw_input('Enter \'y\' or \'n\' to continue: ')
                    if choice == 'y' or 'n':
                        break'''

            readFileLoop(choice, dire)

        else:
            raw_input('No snippet with that name exists. Enter to continue: ') #add options to retry, create snippet or go back
            readMenu()

    elif choice == '0':
        os.system("clear")
        print Menu 

def creationMenu():             ###### Menu to create, edit and delete a snippet ######
        os.system("clear")

        print CreateMenu
        choice = raw_input('--: ')

        if choice == '1':               ### Create a snippet
            os.system("clear")
            print create()
            print creationMenu()

        elif choice == '2':
            os.system("clear")          ### Edit a snippet
            print ("teh editon staton")
            raw_input()
            print creationMenu()

        elif choice == '3':
            os.system("clear")          ### Delete a snippet
            print ("Deletion staton")
            raw_input()
            print creationMenu()

        elif choice == '0':             ### Go Back
            os.system("clear")



######## Main loop #######

running = True

print ('Welcome to the code library, please don\'t disturb other readers!\n\n')

while running:  
    mainMenu()

######## Main loop #######

Tl;Dr: Need to write and read multiline text files

Answer 1

The problem that I'm having is the way the multilines are being stored to the file, it's stored in list format eg ['line1', 'line2', 'line3'] which is making it difficult to read as multilines because I can't get it to be read as a list, when I tried it added the whole stored string into one list item. I don't know if I'm writing to the file correctly.

OK, so the problem is with writing the file. You're reading it in correctly, it just doesn't have the data you want. And the problem is in your raw_lines function. First it assembles a list of lines in the result variable, which is good. Then it does this:

result = str(result)
result.replace('[','').replace(']','')

There are two small problems and one big one here.

First, replace :

Return[s] a copy of the string with all occurrences of substring old replaced by new .

Python strings are immutable. None of their methods change them in-place; all of them return a new string instead. You're not doing anything with that new string, so that line has no effect.

Second, if you want to join a sequence of strings into a string, you don't do that by calling str on the sequence and then trying to parse it. That's what the join method is for. For example, if your lines already end with newlines, you want ''.join(result) . If not, you want something like '\\n'.join(result) + '\\n' . What you're doing has all kinds of problems—you forgot to remove the extra commas, you will remove any brackets (or commas, once you fix that) within the strings themselves, etc.

Finally, you shouldn't be doing this in the first place. You want to return something that can be passed to writelines , which:

Write[s] a sequence of strings to the file. The sequence can be any iterable object producing strings, typically a list of strings.

You have a list of strings, which is exactly what writelines wants. Don't try to join them up into one string. If you do, it will run, but it won't do the right thing (because a string is, itself, a sequence of 1-character strings).

So, if you just remove those two lines entirely, your code will almost work.

But there's one last problem: raw_input :

… reads a line from input, converts it to a string (stripping a trailing newline), and returns that.

But writelines :

… does not add line separators.

So, you'll end up with all of your lines concatenated together. You need the newlines, but raw_input throws them away. So, you have to add them back on. You can fix this with a simple one-line change:

result.append(line + '\n')

Answer 2

To read multiple lines from a file, it's easiest to use readlines() , which will return a list of all lines in the file. To read the file use:

with open(directory, 'r') as f:
    lines = f.readlines()

And to write out your changes, use:

with open(directory, 'w') as f:
    f.writelines(lines)

Answer 3

fileList = [line for line in open("file.txt")]

While the previously mention idiom will work for reading files, I like mine. Its short and to the point.