文件操作with语句

Posted 2021-01-05

import sys

data=open("gc.txt","r",encoding="utf-8") #只能读取文件

data=open("gc.txt","w",encoding="utf-8") #写模式创建一个文件（如果文件名相同会覆盖掉）

data=open("gc.txt","a",encoding="utf-8") #只能在文件后面追加

print(data.readline()) #打印一行

print(data.readlines()) #打印成列表

for i in range(5):

print(data.readline())

‘‘‘
#low 方法 适合读小文件
for index,line in enumerate(data.readlines()):#取出下标和对应的值
if index==9:
print("----ooo----")
continue
print(line.strip())

#high bige 度一行覆盖一行，常用牛逼方法
count=0
for loo in data:
if count==4:
print(‘-----You will die-----‘)
count+=1
continue
print(loo)
count+=1
‘‘‘

#光标使用

f=open("gc.txt","r",encoding="utf-8")

print(f.tell())#打印光标当前位置

print(f.read(5))

print(f.readline())

print(f.tell())

f.seek(0)#光标移动端指定位置

print(f.encoding)#打印所用字符编码

print(f.flush())#强制刷新

f.truncate(10)#截断，从开头开始截，光标移动后再截断没用，依然从头开始算。

#f=open("yesok2",‘r+‘,encoding="utf-8")#文件句柄 读写，在最后追加
#f=open("gc.txt",‘w+‘,encoding="utf-8")#文件句柄 写读，覆盖原文件（创建新文件）后写。只会在最后追加。文件观后再打开写入会覆盖
#f=open("yesok2",‘a+‘,encoding="utf-8")#文件句柄 追加读写

f=open("yesok2",‘rb‘) #文件句柄 以二进制读文件

f=open("yesok2",‘wb‘) #文件句柄 以二进制写

f=open("yesok2",‘ab‘) #文件句柄 以二进制追加

f.write("hello ".encode()) #二进制写读

f.close

f=open("gc.txt","r",encoding="utf-8")

f1=open("gc1.txt","w",encoding="utf-8")

for line in f:

if "是挣扎的自由" in line:

line=line.replace("是挣扎的自由","有我无敌天下")

f1.write(line )

#f.close()
#f1.close()

#find_str=sys.argv[1]
#replace_str=sys.argv[2]
#for line in f:
#if find_str in line:
#line=line.replace(find_str,replace_str)
#f1.write(line)
#f.close()
#f1.close()

with语句

with open("gege",‘r‘,encoding="utf-8") as f:
for line in f:
print(line) #执行完自动关闭文件

同时打开文件不建议这么写

with open("gege",‘r‘,encoding="utf-8") as f,open("gege",‘r‘,encoding="utf-8") as f:
pass

打开多个文件建议这么写

with open("gege",‘r‘,encoding="utf-8") as f,
open("gege",‘r‘,encoding="utf-8") as f2:
for line in f:
print(line) #执行完自动关闭文件