文件操作的其他方法

Posted 2021-03-05 zhangtieshan

一、文件操作的其他方法

1、读相关操作

1.1、readline:一次读yi行

with open(r'a.txt',mode='rt',encoding='utf-8') as f :
    res1=f.readline()
    res2=f.readline()
    print(res1)
    print(res2)

with open(r'a.txt',mode='rt',encoding='utf-8') as f :
    while True:
        line = f.readline()
        if len(line) == 0:
            break
        print(line)

1.2、readlines:读取整个文件的所有行，保存在一个列表中

with open(r'a.txt',mode='rt',encoding='utf-8') as f:
    res=f.readlines()
    print(res)

注意：f.read()与f.readlines()都是将内容一次性读入内存，如果内容过大会导致内存溢出

2、写相关操作

2.1、writelines()

with open('d.txt',mode='wt',encoding='utf-8') as f:
    # f.write('1111
2222
3333
')
    l=['aaaa
','bbbbb
','cccc
']
    # for line in l:
    #     f.write(line)
    f.writelines(l)

2.2、写操作补充

2.2.1 如果是纯英文字符，可以直接加前缀b得到bytes类型

with open('h.txt', mode='wb') as f:
    l=[
        b'111aaa1
',
        b'222bbb2
',
        b'333eee3
',
    ]
    f.writelines(l)

2.2.2 ‘上‘.encode(‘utf-8‘) 等同于bytes(‘上‘,encoding=‘utf-8‘)

with open('h.txt', mode='wb') as f:
    l=[
        bytes('上',encoding='utf-8'),
        bytes('中',encoding='utf-8'),
        bytes('下',encoding='utf-8')
    ]
    f.writelines(l)

2.2.3 flush：将每次写的内容立即存入硬盘

with open('i.txt',mode='wt',encoding='utf-8') as f:
    f.write('哈')
    f.flush()
    f.write('哇')
    f.flush()
    f.write('呀')
    f.flush()

2.3 其他方法了解

with open('j.txt',mode='wt',encoding='utf-8') as f:
    print(f.readable())  #判断文件是否可读
    print(f.writable())  #判断文件是否可写
    print(f.encoding)  #文件的编码方式
    print(f.name)  #文件名