ⅩⅡ：操作文件的方法

一：读相关操作

1、readline：一次读一行

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

    while True:
        line=f.readline()
        if len(line) == 0:
            break
        print(line)

2、readlines：

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

强调：

• 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，若还想将内容全读入内存，

二：写相关操作

# 1.f.writelines()：

with open('h.txt',mode='wt',encoding='utf-8') as f:
    f.write('1111
222
3333
')

    l=['11111
','2222','3333',4444]
    l=['11111
','2222','3333']
    for line in l:
        f.write(line)
    f.writelines(l)

with open('h.txt', mode='wb') as f:
    l = [
        '1111aaa1
'.encode('utf-8'),
        '222bb2'.encode('utf-8'),
        '33eee33'.encode('utf-8')
    ]

    # 补充1：如果是纯英文字符，可以直接加前缀b得到bytes类型
    l = [
        b'1111aaa1
',
        b'222bb2',
        b'33eee33'
    ]

    # 补充2：'上'.encode('utf-8') 等同于bytes('上',encoding='utf-8')
    l = [
        bytes('上啊',encoding='utf-8'),
        bytes('冲呀',encoding='utf-8'),
        bytes('小垃圾们',encoding='utf-8'),
    ]
    f.writelines(l)

# 3、flush：
with open('h.txt', mode='wt',encoding='utf-8') as f:
    f.write('哈')
    # f.flush()

# 4、了解
with open('h.txt', mode='wt',encoding='utf-8') as f:
    print(f.readable())
    print(f.writable())
    print(f.encoding)
    print(f.name)

print(f.closed)