Python学習3月8日【pythonプログラミング入門から実践へ】---ノート(1)

   ：       

#      ，               
#      ，              
#    ， python       ，           
#    json,           ，            

10.1         

#10.1.1       



#10.1.3     

##  For  
# filename= 'pi_digits.txt'
# with open (filename) as file_object:#      with， python            。
#     for line in file_object:#        ，                       
#         print(line.rstrip())

#10.1.4                

# filename = 'pi_digits.txt'
# with open(filename) as file_object:
#     lines = file_object.readlines()
# for line in lines:
#     print(line.rstrip())

#10.2.1     

filename = 'programming.txt'

with open (filename,"w") as file_object:
    file_object.write(" I love programming.")


#10.2.3     

# ‘a'       ，                

filename = 'programming.txt'

with open (filename,"a") as file_object:
    file_object.write("  also love finding meaning in large datasets.
")
    file_object.write(" i love creating apps that can run in a browser.
")

#10.3   

#10.3.1   ZeroDivisionError  

# try:
#     print(5/0)
# except ZeroDivisionError:
#     print(" You can't divide by zero ")

10.3.3         

#try-except-else            ：

#  FileNotFoundError   


#    try-except              。

filename= 'alice.txt'
try:
    with open(filename) as f_obj:##            
        contens = f_obj.read()## read（）       contens  
except FileNotFoundError:#    FileNotFoundError          
    msg="Sorry , the file " + filename + " does not exist."
    print(msg)##        

10.3.4 else   

#try-except-else            ：

print("Give me two numbers , and i'll divide them .")
print("Enter 'q' to quit .")

while True:
    first_number=input("
First number: ")
    if first_number=='q':
        break
    second_number=input("
Second number: ")
    try:                                        ###### try-except-else        ，python    try       ；

        answer = int(first_number) / int(second_number)###            
    except ZeroDivisionError:　　　　　　　　　　　　#except     python，  ZeroDivisionError       ，              。

        print("You can't divide by 0!")
    else:　　　　　　　　　　　　　　　　　　　　　　　####                try   ；     try                ，    else    

        print(answer)

10.3.6    

#                      ，               
# title = "Alice in Wonderland "
# a=title.split()#                 。
# print(a)


10.3.7       

def count_words(filename):
    "              "
    try:
        with open (filname) as f_obj:
            contents= f_obj.read()
    except FileExistsError:     #             ，   except           ，    pass  
        msg="Sorry , the file" + filename + " does not exist."
        print(msg)
    else:
        #             
        words= contents.split()#            ，  ：               。
        num_words = len(words)
        print("The  file "  +  filename + "has about" + str(num_words) + "words")

filename = ['alice.text','siddhartha.txt','moby_dick.txt']
for filename in filenames:
　　count_words(filename)

       ，  try-except             ：       traceback；                。


10.4    


#  json        python          ，                  。
#json        (JavaScriptObject Notation)       Javascript  。

import json
numbers=[2,3,4,56,15]

filename = 'number.json'   ##       。json           JSON  。
with open(filename,'w')as f_obj:
    json.dump(numbers,f_obj)　　　　　　##  json.dump()      ：                    。

print(numbers)

           ，   load  dump 。

import json
filename = 'number.json'
with open(filename) as f_obj:
    numbers=json.load(f_obj)　　　　　　##      json.load()     numbers.json    ，        numbers 。

print(numbers)

import json

def get_stored_username():
    ##        ，    
    filename = 'username.json'
    try:
        with open(filename) as f_obj:
            username = json.load(f_obj)
    except FileNotFoundError:
        return None
    else:
        return username
def greet_user():
    #    ，      
    username= get_stored_username()
    if username:
        print("Welcome back,"  +  username + "!")
    else:
        username = input("What is your name ?")
        filename ='username.json'
        with open(filename,'w')as f_obj:
            json.dump(username,f_obj)
            print("We'll remember you when you come back,"  + username + "!")

greet_user()

10.4.3  


   remember_me.py        ，               。    greet_user(),          

###         ，       



      get_stored_username() ,               （       ),       get_stored-username（）,                   。

        ！！！！

import json

def get_stored_username():
    ##        ，    
    filename = 'username.json'
    try:
        with open(filename) as f_obj:
            username = json.load(f_obj)
    except FileNotFoundError:
        return None
    else:
        return username

def get_new_username():
    #         
    uesrname1=input("What is your name?")
    filename='username1.json'
    with open(filename,'w')as f_obj:
        json.dump(username,f_obj)
    return username

def greet_user():
    #    ，      
    username= get_stored_username()
    if username:
        print("Welcome back,"  +  username + "!")
    else:
        username=get_new_username()
        print("We'll remember you when you come back,"  + username + "!")

greet_user()