一、文件权限扩展
1. "r+"
r+ 写入的位置是 当前光标所在位置，会直接改写当前位置的值
r+ 可以续写么？ 可以，但是必须把光标挪到最后
r 没有创建文件的能力
1 r_file = open("cc.txt", "r+", encoding="utf-8") 2 r_file.write("666\n") 3 r_file.close() 4 5 r_file1 = open("cc.txt", "r+", encoding="utf-8") 6 print(r_file1.read()) 7 print(r_file1.tell()) 8 r_file1.write("333\n") 9 r_file1.close()
2."w+"
w+ 拥有写入权限，可以创建文件
w 所有的write操作是先写在内存中，只有结束的时候才会执行进去
w+ 和 r+ 的区别是 r+ 只在当前位置写入，w+ 是全部重写内容
1 w_file1 = open("www.txt", "w+", encoding="utf-8") 2 w_file1.write("aaa\n") 3 w_file1.close() 4 5 w_file = open("www.txt", "w", encoding="utf-8") 6 w_file.write("123\n") 7 w_file.write("123\n") 8 w_file.write("123\n") 9 w_file.write("123\n") 10 w_file.write("123\n") 11 w_file.close()
3"a+"
a 是追加 a+ 追加
1 a_file = open("a.txt","a",encoding="utf-8") 2 a_file.write("555\n") 3 a_file.close() 4 5 a_file1 = open("a.txt", "a+", encoding="utf-8") 6 a_file1.write("333\n") 7 a_file1.close()
二、with
自动管理上下文
数据库连接
多线程
1 # 写文件的函数 filename,content 2 def write_file(filename:str,content:str,type:int=1): 3 with open(filename,'w') as fw: 4 fw.write(content) 5 6 def read_file(filename): 7 with open(filename,) as fw: 8 return fw.read() 9 # 调用函数写入文件、读取文件 10 write_file("a.txt","cheng成",2) 11 12 print(read_file("a.txt"))
