6.文件操作

'''
file = open("test",'r',encoding="utf-8")

    'r'       open for reading (default)
    'w'       open for writing, truncating the file first
    'x'       create a new file and open it for writing
    'a'       open for writing, appending to the end of the file if it exists
    'b'       binary mode
    't'       text mode (default)
    '+'       open a disk file for updating (reading and writing)
    'U'       universal newline mode (deprecated)
'''

#data = file.read()#一次性读到底部

'''
读取操作演示
'''

file = open("test","r",encoding="utf-8")

'''
读取前几行
for l in range(5):
    print(file.readline().strip())

读取指定某行的内容 只适合读小文件 
for index,line in enumerate(file.readlines()):
    if index == 9:
        print(line)
        
自动开启迭代,效率比较高，推荐使用
for line in file:
    print(line)

count = 0
for line in file:
    if count == 9:
        print(line)
    count+=1
'''

#每次读的字符数
print(file.read(2))
print(file.tell())

#指定读取几个字符
print(file.read(4))

#光标移动
print(file.seek(0))
print(file.read(2))

#打印文件编码
print(file.encoding)


file.close()

'''打印进度条

import  sys,time

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


# f  = open("test","a",encoding="utf-8")
# #从头开始截取几个字符,参数为null则是清空文件
# #file.truncate(10)
# f.truncate(3)

'''
常用到
既可以读又可以写
r+ 读与追加方式写
'''
f = open("test","r+",encoding="utf-8")
print(f.readline())
print(f.write("123r+"))

'''
很少用到
w+ 写读 ,先创建空文件在写
'''

f = open("test","w+",encoding="utf-8")
f.write("w+")

''' 95 a+ 追加读写
'''
f = open("test","a+",encoding="utf-8")


'''
很少用到
rb 读二进制文件
'''
f = open("test","rb",encoding="utf-8")

###########################with 方法自动关闭资源##############

#with open as f1
#with可以自动关闭资源
with   open("test","r",encoding="utf-8") as f1,\
    open("test.bak","w",encoding="utf-8") as f2:
    for line in f1:
        print(line.strip())