第十章文件和异常

#读取文件操作，
# 当前路径
with open('pi.txt') as file:
    print(file.read())
# 绝对路径
with open('D:db.txt') as file:
    print(file.read())

# 这样执行打出来的会多一行空白，是因为每个末尾都有一个换行符
filename='pi.txt'
with open(filename) as file:
    for line in file:
        print(line)
#让圆周率连在一起
filename="pi.txt"
with open(filename) as file:
    lines=file.readlines()
p_string=''
for line in lines:
    p_string+=line.strip()
print(p_string)
print(len(p_string))

#圆周率有你的生日没有
filename="pi.txt"
with open(filename) as file:
    lines=file.readlines()
    p=''
    for line in lines:
        p+=line.rstrip()
birthday=input("Enter you birthday:")
if birthday in p:
    print("Your birthday appears in the first million digits of pi")
else:
    print("not apperas ")

#总结：readLine 从字面意思可以看出，该方法每次读出一行内容，所以，读取时占用内存小，比较适合大文件，该方法返回一个字符串对象。,ReadLines 一起性读取文中所有的行数，并按行返回到list，方便我们遍历
read() ： 一次性读取整个文件内容。推荐使用read(size)方法，size越大运行时间越长

# 写入文件操作
# 指定打开文件时，读取模式r,写入模式w,附加模式a，让你能读取和写入文件的模式r+,如果是省略模式
#则默认只读，如果写入文件不存在，会自动创建，用w时候要小心，如果存在了，会返回对象前清空该文件
filename="li.txt"
with open(filename,'w') as file:
    file.write("I love programming.
")
    file.write("I love programming.
")
#追加模式a
filename="li.txt"
with open(filename,'a') as file:
    file.write("I love dataing.
")
    file.write("I love swiming.
")

#异常,如果Try 中的没有问题，那么就输出try 中的内容，如果有问题，就输出except
try:
    print(5/0)
except ZeroDivisionError:
    print("You can't divide by zero!")

#else 代码块， 依赖于try 执行成功后的代码块都要放在else 代码块中
print("Give me two number, I  will divide it")
while True:
    first_number=input("
 First number:")
    if first_number=='q':
        break
    second_number=input("
 second number:")
    try:
        answer=int(first_number)/int(second_number)
    except ZeroDivisionError:
        print("You can't divie by 0")
    else:
        print(answer)
#文件异常 FileNotFoundError
filename='hell.txt'
try:
    with open(filename) as file:
       contents= file.read()
except FileNotFoundError:
    msg="Sorry,the file "+filename+" not exist"
    print(msg)

# 统计文本有多少个单词，这些文件可能不存在
def count_words(filename):
  try:
    with open(filename) as file:
        contents=file.read()
  except FileNotFoundError:
        msg="sorry,the file not exist"
        print(msg)
  else:
        word=contents.split()
        numwords=len(word)
        print(filename+" has about "+str(numwords))
filename=['alice.txt','li.txt','pi.txt']
for f in filename:
    count_words(f)
    
    
    
#失败时一声不吭,pass 这个表示直接略过，pass 就是不做任何操作
def count_words(filename):
  try:
    with open(filename) as file:
        contents=file.read()
  except FileNotFoundError:
       pass
  else:
        word=contents.split()
        numwords=len(word)
        print(filename+" has about "+str(numwords))
filename=['alice.txt','li.txt','pi.txt']
for f in filename:
    count_words(f)

还有json操作，但是我认为书上说的浅。回头补资料