文件操作

1. file函数

---

1.1 open()

fhand = open('mbox.txt')
print (fhand)
//打印地址

1.2Counting Lines in a Files

//数文件中的行数
fhand = open('mbox.txt')
count = 0 
for line in fhand:
  count = count +1
print ('Line count:',count)
>>>Line count: 132045

1.3 Reading the Whole File

//读取文件中的每个字符？
fhand = open('mbox-short.txt')
inp = fhand.read()
print (len(inp))
>>>94626

print (inp[:20])
>>>From stepen.marquar

1.4 Searching Through a File

fhand = open()
for line in fhand:
  if line.startswith('From:')
    print (line)

for line in fhand:
  line = line.rstrip()
  if line.stratswith('From:')
    print (line)
//这个函数可以解决print函数多打空行的问题

fname = input('Enter the file name :')
//我们可以自己输入文件名字

1.5 Bad File Names

//使用try except来发现是否输入了错误的文件名
fhand = input('Enter the file name:')
try: 
  fhand = open(fname)
except::
  print ('File cannot be opened', fname)
  quit()

count = 0 
for line in fhand
  if line.startswith('Subject:'):
    count = count +1
print ('There were ', count ,'subject lines in ', fname)