第三周文件处理和函数------上

===========第一节文件的读写
---文件写
f=open(r'ppp.txt','wt',encoding='utf-8')

print(f.writable())
f.write("dfjjhdffdfdfdfdqqqqqqqqqqq\n")#自己换行\n
f.write("222222222222\n")#自己换行\n

f.close()



#一般在window上面需要添加r,取消window路径的问题
#rt 一般只写r代表省略了t,文本文件text
#图片格式的就不需要编码.
#编码和操作系统有关,windows上面是GBK
# f=open(r'qq.txt','rt',encoding='utf-8')

#写是覆盖
f=open(r'ppp.txt','wt',encoding='utf-8')

print(f.writable())
f.write("dfjjhdffdfdfdfdqqqqqqqqqqq\n")#自己换行\n
f.write("222222222222\n")#自己换行\n
f.writelines(['t333t\n','kk4444kk\n']) #写多行

f.close()

#a 模式文件不存在则创建文件,文件存在则打开文件,把光标移动到文件末尾
f=open(r'ppp.txt','at',encoding='utf-8')

print(f.writable())
f.write("4444444444444444\n")#自己换行\n
f.write("55555555555\n")#自己换行\n
f.writelines(['77777\n','888888\n']) #写多行

f.close()

-------------------一次读出所有文件
f=open(r'ppp.txt','rt',encoding='utf-8')

print(f.read())# 一次读出所有文件,仅仅适用于文件很小的情况

f.close()

-------------------readlines 一次读出放入列表
f=open(r'ppp.txt','rt',encoding='utf-8')

# print(f.read())# 一次读出所有文件,仅仅适用于文件很小的情况
print(f.readlines())# 一次读出所有文件,仅仅适用于文件很小的情况

f.close()

['dfjjhdffdfdfdfdqqqqqqqqqqq\n', '222222222222\n', 't333t\n', 'kk4444kk\n', '4444444444444444\n', '55555555555\n', '77777\n', '888888\n']

-----------------------
f=open(r'ppp.txt','rt',encoding='utf-8')

print(f.readline(),end='')#一行一行的读,多了一个换行符是print的end='',取消print的换行符
print(f.readline(),end='')#一行一行的读,多了一个换行符是print的end='',取消print的换行符

f.close()

---------------------
循环打印出文件内容:

with open(r'ppp.txt','rt',encoding='utf-8') as  f:
    while True:
        if len(f.readline())==0: break
        print(f.readline(),end='')
------------------打印出所有内容,for循环
		
with open(r'ppp.txt','rt',encoding='utf-8') as  f:
    for line in f:
        print(line,end='')
-----------------------------------------		--------------
		
with open(r'tt.txt','rb') as  f:
   print(f.readline().decode('utf-8'))
   
========================= 二进制写txt
with open(r'tt2.txt','wb') as  f:
   print(f.write(('地方和环境').encode('utf-8')))
   
-------------二进制追加写
with open(r'tt2.txt','ab') as  f:
   print(f.write(  ('分担分担').encode('utf-8')  ) )

==================第二节


with open('tt2.txt','r',encoding='utf-8') as f:
   print(type(f))  
默认是读模式,读模式下不可以写.


#一次读出所有文件的内容,第二次读取什么内容也无法读出,光标移动到了末尾,
with open('tt2.txt','r',encoding='utf-8') as f:
   print(f.read())
   print(f.read())

with open('tt2.txt','r',encoding='utf-8') as f:
  print(f.readline())  #读一行
   
 #去除print的默认换行符
 
with open('tt2.txt','r',encoding='utf-8') as f:
   print(f.readline(),end='')
   print(f.readline(),end='')
 
 #读出所有行的内容,每行放入在一个列表
 with open('tt2.txt','r',encoding='utf-8') as f:
   print(f.readlines())
   
====文件写模式很危险会清空文件  >清空

with open('tt2.txt',mode='w',encoding='utf-8') as f:
   pass
   
===读出一个文件写入另一个文件,相当于CP功能.
with open('tt2.txt',mode='r',encoding='utf-8') as r,\
      open('tt3.txt',mode='w',encoding='utf-8') as w:
   for i in r:
      print(i)
      w.write(i)
   

with open('tt2.txt',mode='r',encoding='utf-8') as r,\
      open('tt3.txt',mode='w',encoding='utf-8') as w:

   for i in r:
      print(i)
      w.write(i)
      w.flush()#保证了写入的信息一定被刷新到了磁盘,因为系统有可能攒在内存里面隔一会写入   
   
   
import sys

print(sys.argv) #获取参数

#获取一个参数列表 文件名 和参数顺序
# ['D:\\PycharmProjects\\wadsd\\day3\\文件.py', 'aa', 'bb']
   
import sys

print(sys.argv) #获取参数

_,srcfile,destfile=sys.argv  #第一个参数不要第二三个参数解压.

print(srcfile)
print(destfile)   
   
######cp 命令模仿最终版###################两个encoding 的作用是一个是python文件的编码,一个是处理文件复制文件的编码
#!/usr/bin/env python
#encoding:utf-8
import sys

print(sys.argv) #获取参数

_,srcfile,destfile=sys.argv

print(srcfile)
print(destfile)

#获取一个参数列表 文件名 和参数顺序
# ['D:\\PycharmProjects\\wadsd\\day3\\文件.py', 'aa', 'bb']

with open(srcfile,mode='r',encoding='utf-8') as r,\
      open(destfile,mode='w',encoding='utf-8') as w:

   for i in r:
      print(i)
      w.write(i)
      w.flush()#保证了写入的信息一定被刷新到了磁盘,因为系统有可能攒在内存里面隔一会写入


	  
	  
 ===================================第三节文件的修改

--------模仿vim改文件
#!/usr/bin/env python
#encoding:utf-8
import os
with open('tt2.txt',mode='r',encoding='utf-8') as r,open('.swaptt2.txt',mode='w',encoding='utf-8') as w:
    for i in r:
        #data=i.replace('e','ax is sb')
        w.write(i.replace('e','ax is sb'))
        w.flush()
os.remove('tt2.txt')

os.rename('.swaptt2.txt','tt2.txt')

------------vim高效版本
import os
with open('tt2.txt',mode='r',encoding='utf-8') as r,open('.swaptt2.txt',mode='w',encoding='utf-8') as w:
    for line in r:
        #data=i.replace('e','ax is sb')
        if 'g' in line:
            line=line.replace('g','ax is sb')
        w.write(line)
        w.flush()
os.remove('tt2.txt')

os.rename('.swaptt2.txt','tt2.txt')


=======================第四节文件内光标的移动

---只有这种情况是字符的情况读取,其他都是字节为单位
with open('tt2.txt','r',encoding='utf-8') as  f:
    print(f.read(3))


with open('tt2.txt','rt',encoding='utf-8') as  f:
    print(f.read(1))
    f.seek(0,0) # 0  第一个表示开始的位置0代表文件的开头   第二个参数代表移动的位置 2,从第几个位置开始读,从那里后的几个位置
    print(f.read())
#f.seek移动的是字节不是字符,一个汉字3个字节.只有0模式能在txt模式下使用,2是文件的末尾.
#txt模式下是能用0.

#只有一种情况光标以字符为单位：文件以rt方式打开，read（3）
# with open('c.txt','rt',encoding='utf-8') as f:
#     # print(f.read(6))
#     # print(f.tell())
#     # f.seek(0,0)
#     # print(f.read(6))
#
#     # f.seek(6,0)
#     f.seek(8,0)
#     print(f.read())
----到文件末尾,倒数三个字符.
# with open('c.txt','rb') as f:
#     # f.seek(-3,2)
#     # print(f.tell())
#     f.seek(0,2)
-----------一个读取文件末尾的例子
import time
with open(r'D:\PycharmProjects\wadsd\day3\tt3.txt','rb') as f:
    f.seek(0,2)
    while True:
        line=f.readline()
        if line:
            print(line)
        else:
            time.sleep(1)


===========第五节截断文件把文件从哪里到哪里保留下来

w模式的写会清空文件,a模式才能截断


import time
with open(r'D:\PycharmProjects\wadsd\day3\tt3.txt','a',encoding='utf-8') as f:
   f.truncate(3)
----------从第三个字符清空文件
import time
with open(r'D:\PycharmProjects\wadsd\day3\tt3.txt','a',encoding='utf-8') as f:
   f.truncate(3)