Document processing, registration, login, with

File Handling

What is document processing

Modify the stored information

What is the file

The concept of virtual storage of information provided by the OS (binary to store information)

open a file

f = open(r'文件路径','打开模式',encoding='某种编码')

Modify the file

f.write()

save document

f.flush()

Close the file

f.close()

Three file open mode

r: read mode

f.read () # read all text
f.readline () # read line by line

w: Clear writing mode

f.write()

a: additional writing

f.write

encoding format specified encoding / writing the read file

Open the file in two ways

t: Text

Class files for text
and r / w / a conjunction, do not add encoding

d: Binary

Audio files for
the r / w / a conjunction, do not add encoding

file path

Absolute path

From the beginning of the letter D: \ ss \ ss \ ss.txt

relative path

And execute files belong to the same folder (writing project as much as possible relative path)

with file management context

whit provides an automatic function closes the file, lifting the occupancy of the operating system.

with open('文件路径','打开模式',encoding='编码格式') as f:
    pass

Advanced application file

r +: readable and writable, writing overlay
w +: read-write, clear write
a +: readable and writable, after the default cursor, the cursor can not be read after the data

Cursor movement

== == English one byte characters, Chinese == == a three-byte characters

seek

seek (n) # n bytes moved, default scratch

whence

Only a predetermined (0,1,2) three modes, a header begins with 0, 1 is the start location of the files, the file 2 starts tail

tell

Tell your current location

truncate

truncate (n) #n reserved for the few on the top few

read

Move the cursor to the character as a unit, n is the number of characters, do not write all the default.

registered

count = 0
while count < 3:
    uname = input('输入名字:')
    upwd = input('输入密码:')
    upwd_inp = input('再次输入密码:')
    if not upwd == upwd_inp:
        print('俩次密码不一致')
        count += 1
        continue
    with open(r'jsb.txt','a',encoding='utf8')as fa:
        fa.write(f'{uname}:{upwd}\n')
        fa.flush()
        break

Sign in

uname = input('输入名字:')
upwd = input('输入密码:')
with open(r'jsb.txt','r',encoding='utf8')as fr:
    for jsb in fr:
        name,pwd = jsb.split(':')
        if name.strip() == uname and pwd.strip == upwd :
        print('登入成功')
        break
    else:
        print('登入失败')

File modification

Do not modify a file that only coverage.