Using cPickle

mmcclaf mmcclaf at gmail.com
Fri Feb 6 20:05:36 CET 2009


On Feb 6, 10:25 am, Steve Holden <st... at holdenweb.com> wrote:
> mmcclaf wrote:
> > Hi there,
>
> > I have to make a small database using cPickle. I'm having troubles
> > trying to read in the information if it's more than one line. I'm
> > pretty sure it's in the line "for line in stuff:" Can anyone help me
> > out? Basically the end result is wanting it to look something like
> > what is down below when list is typed in:
>
> > Last name                 First Name                Email Address
> > Doe                          John
> > j... at doe.com
>
> > [code]
> > # @author: Ocdt Murray McClafferty 24656
> > # This will manage a small database using the cPickle module.
> > # It must maintain a list of last names, first names and email
> > addresses, and must let a user interact with the program
>
> > #
> > #!usr/bin/python
> > # -*- coding: utf-8 -*-
>
> > import sys
> > import cPickle
>
> > #
> > format = '%s             %s                  %s'
>
> > try:
> >    filename = sys.argv[1]
> >    input = open(filename, 'r')
>
> > except IOError:
> >    print 'File is not available, will create a new file now'
> >    lastName='Last Name'
> >    firstName='First Name'
> >    email= 'Email'
> >    #input.close()
> >    output=open (filename, 'w')
> >    total = format%(lastName, firstName, email)
> >    cPickle.dump(total,output)
> >    #cPickle.dump(firstName,output)
> >    #cPickle.dump(email,output)
> >    output.close()
> > except EOFError:
> >    print 'File is empty'
>
> > #datas = cPickle.load(input)
>
> > while True:
> >    command=sys.stdin.readline()[:-1]
> >    if command=='list': #lists the data in the file
> >            input = open(filename, 'r')
> >            stuff=cPickle.load(input)
> >            for line in stuff:
> >                    #firstName=cPickle.load(input)
> >                    #email=cPickle.load(input)
> >                    #print repr (lastName).rjust(10), repr(firstName).rjust(20), repr
> > (email).rjust(20)
> >                    stuff=cPickle.load(input)
> >                    print stuff
> >                    print line
>
> >            input.close()
>
> >    if command=='exit' or command=='quit' : #NEVER forget the exit!!!
> >            print 'Save changes? y for Yes, n for No'
> >            commandSave=sys.stdin.readline()[:-1]
> >            if commandSave =='y': #if the user wants to save
> >                    output=open(filename, 'w')
> >                    cPickle.dump(work,output)
> >                    output.close()
> >                    sys.exit(0)
> >            if commandSave =='n': #no save
> >                    input.close()
> >                    sys.exit(0)
>
> >    if command=='add': #adds an entity to the file
> >            print 'Last name?'
> >            lastName=sys.stdin.readline()[:-1]
> >            print 'First name?'
> >            firstName=sys.stdin.readline()[:-1]
> >            print 'Email address?'
> >            email=sys.stdin.readline()[:-1]
> >            work = format%(lastName, firstName, email)
> >            #output=open(filename, 'w')
> >            #data=cPickle.load(output)
> >            #data.append(work)
> >            #output.close()
> >            output=open(filename, 'a')
> >            cPickle.dump(work,output)
> >            output.close()
>
> > [/code]
>
> > All help would be appreciated. I am new to Python and this seems to be
> > quite a challenge for me.
>
> Make sure you use modes "rb" and "wb" when you open the pickle files. If
> you are running on Windows this can make a difference.
>
> regards
>  Steve
> --
> Steve Holden        +1 571 484 6266   +1 800 494 3119
> Holden Web LLC              http://www.holdenweb.com/

I've tried both rb and wb as well as r and w, there appears to be no
difference in the running of the code.



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