文件操作

with open("d:\\python\\a.txt","r",encoding = "utf-8") as fp:    print(fp.read())

class Sample:
    def __enter__(self):
        print("In __enter__()")
        return "Foo"
    def __exit__(self, type, value, trace):
       print("In __exit__()")
def get_sample():
   return Sample()
 
with get_sample() as sample:
    print("sample:", sample)

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
fp = open("d:\\python36\\a.txt","r",encoding = "utf-8")
data = fp.read()
fp.close()
 
print(data)

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
fp = open("d:\\python36\\a.txt","r",encoding = "utf-8")
data = fp.readline()
fp.close()
 
print(data)

>>> fp = open("d:\\python36\\a.txt","r")
>>> while 1:
...     content = fp.readline()
...     print(content)
...     if content == "":
...         break
...
hello world!
 
hello world!
 
hello world!
 
hello world!
 
hello world!
 
hello world!
 
hello world!
 
hello world!
 
>>> fp.close()

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
fp = open("d:\\python36\\a.txt","r",encoding = "utf-8")
#data = fp.readline()
data = fp.readlines()
fp.close()
 
print(data)

>>> fp = open("d:\\python36\\a.txt","r+")
>>> fp.read()
‘test1\ntest2\ntest3\nalex4\nalex5\n\n‘
>>> fp.tell()
37
>>> fp.write("hello")
5
>>> fp.seek(0.0)
0.0
>>> fp.read()
‘test1\ntest2\ntest3\nalex4\nalex5\n\nhello‘
>>> fp = open("d:\\python36\\a.txt","a+")
>>> fp.read()
‘‘
>>> fp.tell()
42
>>> fp.seek(0,0)
0
>>> fp.read()
‘test1\ntest2\ntest3\nalex4\nalex5\n\nhello‘
>>> fp.tell()
42
>>> fp.seek(0,0)
0
>>> fp.write("world!")
6
>>> fp.seek(0,0)
0
>>> fp.read()
‘test1\ntest2\ntest3\nalex4\nalex5\n\nhelloworld!‘
>>> fp.close()
>>> fp = open("d:\\python36\\a.txt","w+")
>>> fp.tell()
0
>>> fp.read()
‘‘
>>> fp.write("hello world!")
12
>>> fp.read()
‘‘
>>> fp.seek(0,0)
0
>>> fp.read()
‘hello world!‘
>>> fp.close()

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
fp = open("a.txt", "r", encoding="utf-8")
data = fp.readlines()
fp.close()
lines = 0
for i in data:
    if "test" in i:
        lines += 1
        #print(i)
print(lines)

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
fp = open("d:\\python36\\a.txt","w",encoding = "utf-8")
fp.write("test1\n")
fp.write("test2\n")
fp.close
 
fp = open("d:\\python36\\a.txt","r",encoding = "utf-8")
print(fp.read())

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
for i in range(1,11):
    fp = open("d:\\python36\\" + str(i)+".txt","w",encoding = "utf-8")
    fp.close()

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
with open("d:\\python36\\a.txt","r",encoding = "utf-8") as fp:
    while(fp.readline()):
        print(fp.readline())

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
fp = open("d:\\python36\\a.txt","w")
print ("文件是否关闭：", fp.closed)
print ("文件的访问模式：", fp.mode)
print ("文件名称：", fp.name)
#关闭文件
fp.close()

>>> fp = open("d:\\python\\a.txt","w")
>>> fp.writelines(["1\n","2\n","3\n"])
>>> fp.close()

testList = [‘test1\n‘, ‘test2\n‘, ‘test3‘, ‘文件操作‘]
fp = open( "c:\\downloads\\ip2.txt",‘w+‘)
print (fp.read(),end="\n")
fp.writelines(testList)
fp.flush()
fp1 = open( "c:\\downloads\\ip2.txt",‘r‘)
print (fp1.read(),end="\n")
fp.close()
fp1.close()

>>> fp = open("d:\\python\\a.txt","r")
>>> print(fp.fileno())
3
>>> fp.close()

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
with open("d:\\python36\\a.txt","r",encoding = "utf-8") as fp:
    print(fp.tell())
    print(fp.readline())
    print(fp.tell())

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
with open("d:\\python36\\a.txt","r",encoding = "utf-8") as fp:
    print(fp.tell())
    print(fp.readline())
    fp.seek(0,0)
    print(fp.tell())

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
with open("d:\\python36\\a.txt","r",encoding = "utf-8") as fp:
    fp.readline()
    fp.seek(3,0)        # 从第三个位置开始读取
    print(fp.tell())
    print(fp.readline())

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
with open("d:\\python\\a.txt","r+",encoding = "utf-8") as fp:
    fp.truncate(10)

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
import linecache
file_content= linecache.getlines(‘d:\\python\\a.txt‘)
print (file_content)
file_content =linecache.getlines(‘d:\\python\\a.txt‘)[0:4]
print (file_content)
file_content =linecache.getline(‘d:\\python\\a.txt‘,2)
print (file_content)
file_content =linecache.updatecache(‘d:\\python\\a.txt‘)
print (file_content)
#更新缓存
linecache.checkcache(‘d:\\python\\a.txt‘)
#清理缓存，如果你不再需要先前从getline()中得到的行
linecache.clearcache()

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
fp = open("d:\\python\\a1.txt","r+")
aList = []
for item in fp:
    if item.strip():
        aList.append(item)
fp.close()
fp = open("d:\\python\\a2.txt",‘w‘)
fp.writelines(aList)
fp.close()

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
import pickle as p
shoplistfile = ‘d:\\shoplist.data‘
# the name of the file where we will store the object
shoplist = [‘apple‘, ‘mango‘, ‘carrot‘]
# Write to the file
f = open(shoplistfile, ‘wb‘)
p.dump(shoplist, f) # dump the object to a file
f.close()
del shoplist # remove the shoplist
# Read back from the storage
f = open(shoplistfile,‘rb‘)
storedlist = p.load(f)
print (‘从文件读取的列表对象：‘,storedlist)

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
import pickle as p
shoplistfile = ‘e:\\shoplist.data‘
# the name of the file where we will store the object
shoplist = [‘apple‘, ‘mango‘, ‘carrot‘]
animallist=[‘hippo‘,‘rabbit‘]
# Write to the file
f = open(shoplistfile, ‘wb‘)
p.dump(shoplist, f) # dump the object to a file
p.dump(animallist,f)
f.close()
del shoplist # remove the shoplist
del animallist
# Read back from the storage
f = open(shoplistfile,‘rb‘)
storedlist = p.load(f)
animallist= p.load(f)
print (storedlist)
print (animallist)