第四章文件操作

第四章 文件操作

4.1 文件基本操作

obj = open('路径',mode='模式',encoding='编码')
obj.write()
obj.read()
obj.close() 

with open...

4.2 打开模式

• r / w / a
• r+ / w+ / a+
• rb / wb / ab
• r+b / w+b / a+b

4.3 操作

• read() , 全部读到内存

• read(1)

  • 1表示一个字符

    obj = open('a.txt',mode='r',encoding='utf-8')
    data = obj.read(1) # 1个字符
    obj.close()
    print(data)

  • 1表示一个字节

    obj = open('a.txt',mode='rb')
    data = obj.read(3) # 1个字节
    obj.close()

• write(字符串)

  obj = open('a.txt',mode='w',encoding='utf-8')
  obj.write('中午你')
  obj.close()

• write(二进制)

  obj = open('a.txt',mode='wb')
  
  # obj.write('中午你'.encode('utf-8'))
  v = '中午你'.encode('utf-8')
  obj.write(v)
  
  obj.close()

• seek(光标字节位置)，无论模式是否带b，都是按照字节进行处理。

  obj = open('a.txt',mode='r',encoding='utf-8')
  obj.seek(3) # 跳转到指定字节位置
  data = obj.read()
  obj.close()
  
  print(data)
  
  
  
  
  obj = open('a.txt',mode='rb')
  obj.seek(3) # 跳转到指定字节位置
  data = obj.read()
  obj.close()
  
  print(data)

• tell(), 获取光标当前所在的字节位置

  obj = open('a.txt',mode='rb')
  # obj.seek(3) # 跳转到指定字节位置
  obj.read()
  data = obj.tell()
  print(data)
  obj.close()

• flush，强制将内存中的数据写入到硬盘

  v = open('a.txt',mode='a',encoding='utf-8')
  while True:
      val = input('请输入：')
      v.write(val)
      v.flush()
  
  v.close()

4.4 关闭文件

文艺青年

v = open('a.txt',mode='a',encoding='utf-8')

v.close()

二逼

with open('a.txt',mode='a',encoding='utf-8') as v:
    data = v.read()
    # 缩进中的代码执行完毕后，自动关闭文件

4.5 文件内容的修改

with open('a.txt',mode='r',encoding='utf-8') as f1:
    data = f1.read()
new_data = data.replace('飞洒','666')

with open('a.txt',mode='w',encoding='utf-8') as f1:
    data = f1.write(new_data)

大文件修改

f1 = open('a.txt',mode='r',encoding='utf-8')
f2 = open('b.txt',mode='w',encoding='utf-8')

for line in f1:
    new_line = line.replace('阿斯','死啊')
    f2.write(new_line)
f1.close()
f2.close()

with open('a.txt',mode='r',encoding='utf-8') as f1, open('c.txt',mode='w',encoding='utf-8') as f2:
    for line in f1:
        new_line = line.replace('阿斯', '死啊')
        f2.write(new_line)