python 代写python、Directory代写python、python编程帮做 、代做python程序设计

日期：2018-09-23 04:19

2018/9/22 My_Phone_Directory

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<font color = 'blue'>Case Study: Making a Phone Directory

1. We build a system where we ask the user to

a. enter record

b. Do a query

c. Load a file

d Save a file

e Exit

2. In our case enter a record means entering a name and a telephone number

3. So our system is simple. We just want a mechanism of storing names and phone numbers

4. Any given a name we want to pull out a phone number

1. There are many problems which have this format.

2. A menu with a list of possible actions that can be taken

3. A mechanism for retrieving data from a file and storing new data that you have

4. We have different routines for the different actions.

5. We have to be very careful on how we select data structures for the different activities

a. In practice the input and output routines have to be carefully designed so as to be idiot proof.

b. We do not want bad data to enter the system.

c. For example we will add some minimal features to ensure the telephone number is entered in a

format that we can use.

d. We may also want to provide some form of assistance to the query function. For example as the

person types a name the computer gives suggestions from the data base.

1. So we have a main program with perhaps 4 functions

2. We probably need a menu function as well

3. What data structures do we need.

2018/9/22 My_Phone_Directory

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In [1]:

def main():

commands = [(1, 'Enter Records'), (2, 'Query'),

(3, 'Load File'), (4, 'Save'), (5, 'Exit')]

myInd = True

while myInd:

for i, s in commands:

print(i, s)

a = input()

if a == "":

break

a = int(a)

if a == 1:

pass

add_entry()

if a == 2:

pass

query()

if a == 3:

pass

loadfile()

if a == 4:

pass

savefile()

if a== 5:

myInd = False

phone={}

main()

1 Enter Records

2 Query

3 Load File

4 Save

5 Exit

5

2018/9/22 My_Phone_Directory

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In [3]:

def add_entry():

a = 'Enter Name: '

a = input(a)

a = a.strip() # Just in case there are spaces at front or back

b = 'Enter Tel. Number'

b = input(b)

b = b.strip() # We want to get rid of leading and ending blank spaces

mylist = b.split() # create a list of numbers ( in case spaces are encountered in the mid

dle)

tel = ''.join(mylist) #concatenates the list

#Put into dictionary

phone[a] = tel

print(' The name ',a,' and tel: ', tel, ' has been added')

return

add_entry()

#ans,tel =add_entry()

#print(ans, tel)

In [4]:

def query():

a = 'Enter Name'

a = input(a)

a = a.strip()

b = phone.get(a)

if b ==None:

print("The name is not available")

else:

print('The Telephone Number of ', a, ' is ', b)

print('')

print('---------------------')

print('')

query()

Enter Name: Peter

Enter Tel. Number 216 368 3849

The name Peter and tel: 2163683849 has been added

Enter NamePeter

The Telephone Number of Peter is 2163683849

---------------------

2018/9/22 My_Phone_Directory

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In [5]:

# Store each

def savefile():

a = input('Enter File Name to save to')

fn = open(a, 'w')

for k in phone: # recall k is the keyword ( name) and phone[k] is the phone number

fn.write(k+'\n')

fn.write(phone[k]+'\n')

fn.close()

savefile() # The file consists of alternate lines of names and phone numbers

In [6]:

def loadfile():

phone = {} # create a dictionary called phone

fname = input('Enter file to load: ')

try:

myfile = open(fname, 'r')

mylist = myfile.readlines() # reads all lines in the file into a list each line

#is an element in the list. It adds\n

for i in range(0, len(mylist), 2):

key_str = mylist[i].strip('\n')

val_str = mylist[i + 1].strip('\n')

phone[key_str] = val_str

print(fname, 'successfully loaded.')

myfile.close()

return phone

except:

print('I could not find the file')

return phone

phone = loadfile()

Enter File Name to save tomyfile

Enter file to load: myfile

myfile successfully loaded.