今日内容概要:
一、with上下文管理(重点)
二、b模式(重点)
三、+模式(了解)
四、文件操作其他方法(重点)
内容详解:
一、with上下文管理
程序运行完成后,必须要有f.close()来关闭文件 # f = open(r"文件路径", mode="rt", encoding="utf-8") # data = f.read(内容) # f.write(内容) # f.close() 使用with,程序运行完成后会自动调用f1.close()回收操作系统,关闭文件 # with open('今日内容.txt',mode='rt',encoding='utf-8') as f1: # data = f1.read() # print(data) # 表示换行,其实蕴含了 with open('今日内容.txt', mode='rt', encoding='utf-8') as f1, open('a.txt', mode='rt', encoding='utf-8') as f2: print('文件1的内容'.center(50, '#')) data = f1.read() print(data) print('文件2的内容'.center(50, '#')) data = f2.read() print(data) # 自动调用f1.close()、f2.close()回收操作系统
二、b模式
1、字符编码解码的知识
# user = input('>>: ') # user="林海峰" user = "林海峰" # 编码操作: # 字符串===utf-8===》bytes res=user.encode("utf-8")#encode 编码 print(res) print(type(res)) # 基于网络发送数据(res) # 解码操作: # bytes====》utf-8=====》字符串 print(res.decode("utf-8"))#decode 解码
2、bytes
with open('a.txt',mode='rb') as f: data=f.read() print(data) print(type(data))
3、t 模式只能用于读文本文件
with open('a.jpg',mode='rt',encoding='utf-8') as f: data=f.read() print(data) print(type(data)) # 图片<---------jpg-------二进制数 # 字符<---------utf-8-------二进制数
4、b模式能用于读所有的文件
with open('a.jpg',mode='rb') as f: data=f.read() print(data)#打印出b'..... print(type(data))#<class 'bytes'> with open('a.jpg', mode='rb') as f: data = f.read() print(data.decode("utf-8"))#报错 print(type(data))#报错
5、 b模式,运行结果为:二进制数
t模式是帮我们解码了 # 字符<---------utf-8-------二进制数
# with open('a.jpg', mode='rb') as src_f, # open('b.jpg', mode='wb') as dst_f: # # data = src_f.read() # # dst_f.write(data) # # for line in src_f: # line=文件中的2行内容 # dst_f.write(line) # with open('b.txt', mode='wb') as f: # user = "林海峰" # res=user.encode('utf-8') # f.write(res) with open('b.txt', mode='wt', encoding="utf-8") as f: user = "林海峰" f.write(user)
三、+模式
可读可写模式,可以省略t,默认就是t模式,读写都是以字符串为单位
r+t
w+t
a+t
可读可写模式,b模式下读写都是以bytes二进制为单位
r+b
w+b
a+b
with open('b.txt',mode='r+t',encoding='utf-8') as f: print(f.read()) f.write("abcdefg") with open('b.txt',mode='w+t',encoding='utf-8') as f: f.write("我爱你中国") print(f.read()) with open('b.txt',mode='a+t',encoding='utf-8') as f: f.write("我爱你中国") print(f.read())
四、文件操作其他方法
1、readline
with open('b.txt', mode='rt', encoding='utf-8') as f: line1=f.readline()#读出第一行 line2=f.readline()#读出第二行 line3=f.readline() line4=f.readline() print(line1,end="")#读出第一行 print(line2,end="")#读出第二行 print(line3,end="") print(line4,end="")
原始方法: l = [] for line in f: l.append(line) 简便方法: l = f.readlines() print(l)
# with open('b.txt', mode='wt', encoding='utf-8') as f: # f.write("1111 2222 333 ") lines=["1111 ","222 ","333 "] #原始方法: for line in lines: f.write(line) #简单方法: f.writelines(lines) f.writelines({'k1':111,'k2':222,"k3":3333})#k1k2k3 f.writelines({'k1':111,1:44444,'k2':222,"k3":3333}) # 报错 f.writelines("hello")#for 循环依次取出 h e l l o f.write("hello")#直接写出hello
3、flush刷新
with open(r'b.txt', mode='wt', encoding='utf-8') as f: # print(f.name) # 获取的是文件的路径 f.write('哈哈哈 ')#操作系统IO行为,攒一波,再发送 # f.flush()#类似于快递急件,有一个发一个