python第十章 文件与异常

#练习题网站：https://www.xz577.com/j/129.html
#文件与异常
#同名文件下可打开
with open('pi.txt') as file_object:
    contents=file_object.read()
    print(contents)
    print(contents.rstrip())
    #read()函数会默认返回空行，所以可以用rstrip()删除
    
#打开同目录下的文件夹中包含的文件
with open('practice\pi.txt') as file_object: #windows使用反斜杠'\'，当然正斜杠也可以
    contents=file_object.read()
    print(contents)
   
#打开任意处的文件：精确查找
with open('C:\CODING\.idea\practice\pi.txt') as file_object:
    #上面的r是为了保证万无一失 因为反斜在python里面为转义字符
    #读取整个文件进行打印
    contents=file_object.read()
    print(contents.rstrip())
    
#逐行读取 遍历整个文件
source='C:\CODING\.idea\practice\pi.txt'

with open(source) as file_object:
    for line in file_object:
        print(line.rstrip()) #因为默认会多空行所以用rtrip
        
 #使用with时，open返回的对象只在with代码块中使用
#如果想要在with之外使用，那么先将文件的各行储存在列表中
source='C:\CODING\.idea\practice\pi.txt'

with open(source) as file_object:
    lines=file_object.readlines()
    #readlines读取每行并存储在列表中
    #注意不是readline！！！

for line in lines:
    print(line.rstrip())
    
#使用文件内的内容 此处是把pi存储在字符串内
pi_string=''
for line in lines:
    pi_string+=line.strip()

print(pi_string)
print(len(pi_string))
                                                                                                              
#如果想把字符串转化为数值 可以使用int或者float
a=float(pi_string)
print(a)

#10.2练习题
source='C:\CODING\.idea\practice\pi.txt'
#将python替换为c
with open(source) as file_object:
    lines=file_object.readlines()
for line in lines:
    print(line.replace('python','c').rstrip())
    
#写入文件
#w为写入模式，r为读取模式，a为附加模式，r+为读取和写入
#注意当文件不存在时，将自动创建，但是当文件
#但是当文件不存在的时候将自动创建文件
#如果文件存在使用了w那么原来的内容将被清除
file_name='p.txt'
with open(file_name,'w') as file_object:
    file_object.write("I love python!!!\nAnd I am so crazy about programmming!!!")
#下面是三种方法：
with open(file_name) as file_object:
    content = file_object.read()
    print(content)
    for line in file_object:
        print(line.rstrip())
    lines = file_object.readlines()
for line in lines:
    print(line.rstrip())    

#写入多行
file_name='p.txt'
with open(file_name,'w') as file_object:
    file_object.write("hello world!\n") #注意此处如果不加\n那么两行就会变成一行
    file_object.write("I love python!")
with open(file_name) as file_object:
    for line in file_object:
        print(line.rstrip())
#附加模式写入多行
with open(file_name,'a') as file_object:
    file_object.write("\nlets do this\n")
    #注意此处前面需要一个\n 否则会和成一行
    file_object.write("I love python!")
with open(file_name) as file_object:
    for line in file_object:
        print(line.rstrip())

#10.3练习 输入访客名称
file_name='hello.txt'
with open(file_name,'w') as file_object:
    a=input("Your name:")
    file_object.write(a)
with open(file_name) as file_object:
    con=file_object.read()
    print(con.rstrip())
    
#10.4练习 多次输入名字 每个名字一行
file_name='hello.txt'
with open(file_name,'w') as file_object:
    active=True
    while active:
        a=input("Enter your name:")
        print("Hello!"+a)
        file_object.write(a+'\n')
        b=input("Do you want to go on? YES PR NO")
        if b!='YES':
            active=False
with open(file_name) as file_object:
    con=file_object.read()
    print(con.rstrip())
    
#使用try-except代码块
try:
    print(5/0)
except ZeroDivisionError:
    print("You cannot divide by Zero!")
#使用代码块避免崩溃
while True:
    f_n=input("First number:")
    if f_n=='q':
        break
    s_n=input("Second number:")
    if s_n=='q':
        break
    try:
        answer=int(f_n)/int(s_n)
        print(answer)
    except ZeroDivisionError:
        print("You cannot do this!")
#当然也可以使用else
try:
        answer=int(f_n)/int(s_n)
except ZeroDivisionError:
        print("You cannot do this!")
else:
    print(answer)
   
#处理FileNotFoundError
file_name="pppp.txt"
try:
    with open(file_name) as file_o:
        con=file_o.read()
        print(con.rstrip())
except FileNotFoundError:
    print(file_name+".txt does not exist!")
    
#分析文本
file_name="hello.txt"
try:
    with open(file_name) as f_o:
        con=f_o.read()
except FileNotFoundError:
    print("Sorry! The file cnnot be found!")
else:
    words=con.split()
    #split将字符串按照空格/行 切成列表
    s=len(words)
    print("The file "+file_name+".txt has about "+str(s)+" words.")              
        
#为了方面使用 可以设置函数
def count(file_name):
    try:
        with open(file_name) as f_o:
            con = f_o.read()
    except FileNotFoundError:
        print("Sorry! The file cnnot be found!")
    else:
        words = con.split()
        # split将字符串按照空格/行 切成列表
        s = len(words)
        print("The file " + file_name + ".txt has about " + str(s) + " words.")

file_name="hello.txt"
count(file_name)

#加循环
file_collection=['hello.txt','pp.txt','hahah.txt']
for file_name in file_collection:
    count(file_name)            

#自主选择报告哪些程序错误
try:
    --snip--
except:
     pass
else:
    --snip--
    
#10.6+10.7 练习 加法运算 实现多次输入 错误提示
def adddd(a,b):
    try:
        a=int(a)
        b=int(b)
    except ValueError:
        print("Please enter numbers instead of text.")
    else:
        print(a+b)
while True:
    a=input("Enter the first number:")
    b=input("Enter the second number:")
    adddd(a,b)
    c=input("Go on or not?YES OR NO")
    if c!="YES":
        break    

#10.8练习 读取文件 异常
file_name=['cats.txt','dogs.txt','hh.txt']
with open(file_name[0],'w') as file_o:
    file_o.write("mory\njojo\nhapo")
with open(file_name[1],'w') as file_o:
    file_o.write("mmory\njkkojo\nhhhhapo")
def read_name(a):
    try:
        with open(i) as ob:
            con=ob.read()
            print(con.rstrip())
    except FileNotFoundError:
        print("The file "+i+" cannot be found.")
for i in file_name:
    read_name(i)
    
#存储数据
#使用json模块来进行存储：将数据存储在文件对象中，格式是列表
import json
numbers=[2,3,4,5]
file_name='numbersjson.txt'
with open(file_name,'w') as ob:#借助ob对象最终把数据存储在number.json里面
    json.dump(numbers,ob)
#用load函数来读出
with open(file_name) as ob:
    number=json.load(ob)
print(number)    

#保存和读取用户输入数据+重构
import json
def get_user():
    file_name='usernamer.txt'
    try:
        with open(file_name) as file_ob:
            username=json.load(file_ob)
    except FileNotFoundError:
        username=input("What's your name?")
        with open(file_name,'w') as file_ob:
            json.dump(username,file_ob)
        print("We will remember when you are back,"+username+"!")
    else:
        print("Welcome back!"+username)

get_user()
#进而在另一个.py模块中
import ha
ha.get_user()

#函数进一步的重构
import json
def get_user_stored():
    file_name='userna.txt'
    try:
        with open(file_name) as file_ob:
            username=json.load(file_ob)
    except FileNotFoundError:
        return None
    else:
        return username

def greet_use():
    username=get_user_stored()
    if username:
        print("Welcome back!" + username)
    else:
        username=input("What's your name?")
        file_name = 'userna.txt'
        with open(file_name,'w') as file_ob:
            json.dump(username,file_ob)
        print("We will remember when you are back,"+username+"!")
greet_use()

#函数进进一步的重构
import json
def get_user_stored():
    file_name='userna.txt'
    try:
        with open(file_name) as file_ob:
            username=json.load(file_ob)
    except FileNotFoundError:
        return None
    else:
        return username

def get_new_name():#函数定义时的括号以及冒号！！！
    username = input("What's your name?")
    file_name = 'userna.txt'
    with open(file_name, 'w') as file_ob:
        json.dump(username, file_ob)
    return username

def greet_use():
    username=get_user_stored()
    if username:
        print("Welcome back!" + username)
    else:
        username=get_new_name()
        print("We will remember when you are back,"+username+"!")

greet_use()
#重构是为了目的性更强

#10.12 功能：
#记录用户输入数字；
#存储自定义文件内；
#如果不输入数字提示并且可以重新输入
#可以多次循环输入
#纪念一下这个实现完整功能的程序！！奥利给！！
import json

def num_stored():
    try:
        f_n=input("What's your favorite number?\n")
        with open(file_name,'w') as ob:
            json.dump(f_n,ob)
        f_n = int(f_n)
    except ValueError:
        print("Enter number please~")
        return 0
def read_num(file_name):
    with open(file_name) as ob:
        con=json.load(ob) #有参数！！！
    print("I know your favorite number is "+str(con)+".")
def enter_num(file_name):
    while True:
        num_stored()
        read_num(file_name)
        a=input("\nGO ON OR NOT? YES OR NO\n")
        if a!="YES":
            break
file_name=input("where you want to store your number?\n(plz end with'.txt')\n")
mm=num_stored()
while True:
    if mm==0:
        num_stored()
    else:
        enter_num(file_name)
    oo=input("what to stop?YES OR NO")
    if oo!='YES':
        break
        
#10.13 实现
#询问老名字是否是新用户的名字，如果不是，提示重新输入
import json

def username_stored():
    username=input("What's your name?")
    print("Hello! We will remember your name when you come back next time, "+username+"!")
    file_name='hello.txt'
    with open(file_name,'w') as ob:
        json.dump(username,ob)
    return username

def username_out():
    file_name = 'hello.txt'
    with open(file_name) as ob:
        username=json.load(ob)
    return username

def greet_comer():
    old_name=username_out()
    greet=input("Hello! Is "+str(old_name)+" your name?\nY or N\n")
    if greet != 'Y':
        username_stored()
    print(username_out())

greet_comer()
#在另外一个同名文件夹下可以使用上面的函数
#只用greet_comer()就可以
#重构的好处是程序明确便于后期的修改 以及一个特定函数可以不断嵌套在其他函数里面 多次使用！
import ha
ha.greet_comer()