[Tutor] writing & reading files

[Frank Holmes]

Still working with this little phonebook program.  When it runs, if 
'phoneyold' doesn't exist it creates it and writes data to file. Problem is, 
if I close the program, open it again and again add entries it overwrites 
the file and none of the previous entries exist. I have tried replacing the 
'w' in f=open('phoneyold','w') with 'a' to append to the file (problem is it 
is a dictionary) but although when I check the data file the entry is there, 
I cannot retrieve it. I have also tried 'w+' to append, but again all 
previous data is dumped when I add. Again I am stumped. How can I add data, 
close the file, re open it , add again and not dump previous data?
import pickle

def add_name():
    print 'Enter Name:'
    dname=raw_input()
    print 'Facility:'
    fname=raw_input()
    print 'phone1:'
    hnum=raw_input()
    if hnum == " " :       #in no huntline entered, hunt =NONE
        hnum='none'
    print'phone2:'
    ph=raw_input()
    print 'Pager:'
    pg=raw_input()
    print 'cell:'
    cop=raw_input()
    print 'Comments:'
    com=raw_input()
    l=(dname, fname, hnum, ph, pg, cop, com)
    d1[dname]=l
    f=open('phoneyold','w')
    pickle.dump(d1,f)
    f.close()



def get_name():
    print "enter name to search"
    name=raw_input()
    f=open('phoneyold','r')
    p_d1=pickle.load(f)
    if name in p_d1.keys():
        g= p_d1[name]
        print 'Name:', g[0]
        print
        print 'place:', g[1]
        print
        print 'phone1:', g[2]
        print
        print 'Phone2:',g[3]
        print
        print 'Pager:', g[4]
        print
        print 'cell:', g[5]
        print
        print 'Comments:',g[6]
    f.close()


d1={}
while 1:
    print
    print "Hello, welcome to Docsearch."
    print
    print "Please enter selection:"
    print "Type '1' to search"
    print
    print "Type '2' to add name to database or 'quit' to exit"


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