python --文件操作模式详解

#f= open(r"aaa/a.txt",mode='rt') # f的值是一种变量，占用的是应用程序的内存空间,此时牵扯的是两个方面的资源
#print(f)

##2.操作文件：读/写文件,应用程序对文件的读写请求都是向操作系统调用，然后由操作系统控制把硬盘把输入读入内存，或者写入硬盘
#res=f.read()
#print(res)

#关闭文件 z
#f.close()"""回收操作系统资源，f 还存在"""
#f变量还存在，但是不能再读了
#del f """回收应用程序程序资源"""


#文件对象又称为文件句柄
# with open("a.txt",mode='rt') as f1:
#     res=f1.read()
#     print(res)

# with open("a.txt",mode='rt') as f1,open("b.txt",mode='rt') as f2:
#     res1=f1.read()
#     res2=f2.read()
#     print(res1)
#     print(res2)

"""指定字符编码"""
"""t 文本（默认的模式）
1。 读写都是以str (unicode)为单位的
2。文本文件
3。必须指定encoding='utf-8'"""

# 没有指定encoding 参数操作系统会使用自己的默认的编码，
# Linux 和mac 默认使用utf-8
# Windows默认gbk
# with open ('c.txt',mode='rt',encoding='utf-8') as f:
#     res=f.read() #t模式会将f.read（）读出来的结果解码成unicode
#     print(res,type(res))
#
#内存：utf-8格式的二进制----解码--->unicode
#硬盘（c.txt 内容 utf-8格式的二进制）

#以t 模式为基础进行内存操作
##1.rt

在本python文件的目录下创建一个name.txt的文本文件，
izhan:1005

inp_username = input("please input your name:").strip()
inp_password = input("please input your password:").strip()
 with open("name.txt",mode='rt',encoding='utf-8') as f:
     res=f.read()
     print(res)
     username,password=res.split(":")
     print(username)
     print(password)
 print(inp_username)
 print(inp_password)
 if inp_username == username and inp_password == password:
     print("congratulations! you can login")
 else:
     print("sorry! the password is wrong or has no this user")

please input your name:izhan
please input your password:1005
izhan
1005
izhan
1005
congratulations! you can login

随便输入看看：
please input your name:dandan
please input your password:0711
izhan
1005
dandan
0711
sorry! the password is wrong or has no this user

Process finished with exit code 0

再创建一个name.txt 文件

izhan:1005
lili:1111
dandan:0711
另外：python spit 的学习：

https://www.cnblogs.com/clairedandan/p/10926173.html

inp_username = input("please input your name:").strip()
inp_password = input("please input your password:").strip()

with open("name.txt",mode='rt',encoding='utf-8') as f:
    for line in f:
        print(line,end='') # 没有end='',结果就会一行一行中间有一行空的。
        username,password=line.strip().split(":")
        # print(username)
        # print(password)
        if inp_username == username and inp_password == password:
            print("login successfully")
            break
    else:
        print("账号错误")

please input your name:lili
please input your password:0711
izhan:1005
lili:1111
dandan:0711账号错误

Process finished with exit code 0

please input your name:izhan
please input your password:1005
izhan:1005
login successfully

Process finished with exit code 0

 

"""w:只写模式，当文件不存在时会创造空文件，当文件存在时会清空文件，"""
# with open("d.txt",mode="wt",encoding="utf-8") as f:
# #    f.read()"""报错，不可读"""
#     f.write("hahaha\n")
#     f.write("hello\n")
#     f.write("wwwwww\n")
##如果重新打开文件，则会清空之前的内容，如果连续write，则会连续写的

"""3.a 只追加写，"""
# with open("a.txt",mode="at",encoding="utf-8") as f:
# #    f.read() 不能读
#     f.write("hahahahah\n")
#     f.write("enenenenen\n")
#     f.write("oooooo\n")

"""a  重新打开文件，不会清空文件内容，会将文件指针直接移动到末尾
a 文件一直用作记录日志，注册功能"""
"""a 模式注册功能"""
# name=input("please input your name:")
# pwd=input("please input your password:")
# with open("db.txt",mode="at",encoding="utf-8") as f:
#     f.write("{}:{}\n".format(name,pwd))

 

w 可以用做文本文件的copy

with open("e.txt",mode="rt",encoding="utf=8")as f1,\
    open("f.txt",mode="wt",encoding="utf-8")as f2:
    res=f1.read()
    f2.write(res)

src_file=input("源文件文件：")
dst_file=input("目标文件：")
with open(r"{}".format(src_file),mode="rt",encoding="utf=8")as f1,\
    open(r"{}".format(dst_file),mode="wt",encoding="utf-8")as f2:
    res=f1.read()
    f2.write(res)

/usr/local/bin/python3.8 /Users/futantan/PycharmProjects/S14/文件知识/文件处理.py
源文件文件：/Users/futantan/PycharmProjects/S14/文件知识/a.txt
目标文件：/Users/futantan/PycharmProjects/S14/a_copy.txt

Process finished with exit code 0

 此时就可以发现有一个copy的文件了