Python学习之路：文件操作之增删改查

f = open("yesterday","r",encoding="utf-8")
#print(f.read())
#for i in range(5):
#    print(f.readline()) #打印前5行

#low loop
'''
for index,line in enumerate(f.readline()):
    if index == 9:
        print('---------我是分割线---------')
        continue
    print(line.strip())
'''

# high bige
'''
count =0
for line in f:
    if count==9:
        print('---------我是分割线-----')
        count +=1
        continue
    print(line) #效率最高，一行一行的读
    count +=1
'''
f =open("yesterday2","w",encoding="utf-8")
f.write("hello1
")
f.write("hello2
")
f.write("hello3
")
f.flush()#实现数据从缓存刷到硬盘

'''
print(f.tell()) #查询光标位置
print(f.readline())
print(f.tell())#查询光标位置,按字符计数
print(f.read(5))
print(f.tell())
f.seek(0)#光标回到某个字符位置
print(f.readline())
f.seek(10)
print(f.readline())
print(f.encoding)#打印文件编码
print(f.fileno()) #读取文件编号
#print(f.flush())
print(dir(f.buffer))
'''

'''#进度条实现
import sys,time

for i in range(50):
    sys.stdout.write("#")
    sys.stdout.flush()
    time.sleep(0.1)
'''

f = open("yesterday","a+",encoding="utf-8")#追加读写
#f.truncate(10) #截断
f.seek(10)
f.truncate(20)

#可以打开，追加
f = open("yesterday","r+",encoding="utf-8")#读写
print(f.readline())
print(f.readline())
print(f.readline())
print(f.tell())
f.write('--------niu----------')

#用处不大
f = open("yesterday","w+",encoding="utf-8")#写读
f.write('--------niu----------1
')
f.write('--------niu----------2
')
f.write('--------niu----------3
')
print(f.tell())
f.seek(10) #不能在中间插入，只能继续往后写，或者覆盖之前的
print(f.tell())

#使用场景：网络传输只能用二进制
f = open("yesterday","rb")#以二进制格式读文件
print(f.readline())
print(f.readline())
print(f.readline())

f = open("yesterday","wb")#以二进制格式写文件
f.write("hello binary
".encode())

f = open("yesterday","ab")#以二进制格式追加文件