Stupid methodology python (EX1-17)--%,input, unpack, read, write files

Tips: alt+3 can be multi-line annotation alt+4 multiline uncomment, F5 run, cmd directly enter python-m Pydoc can open the Help document, or can be directly followed by a function can be queried using such as Python-m Pydoc round

1%r

Percent-semicolon unconventional usage:

Formatter = "%r%r%r%r"

Print Formatter% (1, 2, 3, 4)

Compare%r with%s. Have you noticed. %r prints what you write in the script, and%s prints what you should see.

2 input ()

There is no raw_input () function in the Python3, and the input () is used directly instead

You can add a hint in parentheses, such as: Age=input (' age? ')

3 parameters, Solution package (ex13)

From sys import ARGV
A,b,c,d = argv
Print (' 1 ', a)
Print (' 2 ', b)

Print (' 3 ', c)

Print (' 4 ', D)

Then open with >>>python 1.py first 2nd 3rd #要理解到1 at the command prompt. PY is actually a parameter

So you can "unpack the things in the argv and give all the arguments to the variable name on the left."

4 read files (ex15)

From sys import ARGV #调用sys的argv

Script,filename= argv #用argv获取文件名, script,filename only variable name does not affect the random

Txt=open (filename) #打开输入的第二个参数对应文件

Print (' Here is your file%r. '%filename) #读取第二个参数对应文件的名字
Print (Txt.read ()) #显示第二个参数对应文件的内容

Print (' Type the filename again: ') #进行第二种打开文件的方法

File_again=input (' > ') #让输入要打开文件的名字

Txt_again=open (File_again) #打开

Print (Txt_again.read ())

At the command line, enter the >>>python 1.py ex15_sample.txt #输入两个参数, replacing Script,filename respectively

5 The commands to be remembered are as follows:

close– closes the file. Save the file-> with your editor. a meaning.

read– Read the contents of the file. You can assign the result to a variable.

readline– reads a line in a text file.

truncate– Empty The file, please use this command carefully.

Write (stuff) – writes stuff to the file.

6 Writing Files

From sys import ARGV

Script,filename= argv# Get file name with argv
Print (' Wo are going to erase%r. '%filename)
Print (' If you don\ ' t want That,hit ctrl-c (^c). ')
Print (' If you don't want That,hit return ')

Input ('? ')

Print (' Opening the file ... ')
Target=open (filename, ' W ') #写入模式

Print (' Good bye! ')
Target.truncate () #清除内容

# # #前半段是擦除之前的数据, the second half is write data

Print (' Now I am going to ask 3 lines ')

Line1=input (' line1: ') # #此处引号不能去掉, because there is no definition of line1
Line2=input (' line2: ')
Line3=input (' Line3: ')

Print (' I am going to write this to the file. ')

Target.write (line1)
Target.write ("\ n")
Target.write (line2)
Target.write ("\ n")
Target.write (LINE3)
Target.write ("\ n")
###### #此处也可用target. Write (line1 + ' \ n ' + line2 + ' \ n ' + line3) instead, note that write () can only be a string. If multiple strings are used, the print () can be separated by commas, and the ##### #write () can only be added with each string

Print (' and finally, we close it. ')
Target.close ()

7 File Mode

When the default file is opened, it returns a read-only file, and if you want to write it in the file, you must display the definition mode parameter, which is the value Description ' r ' Read mode ' W ' write mode ' which is most commonly used by the mode parameter. A ' Append mode ' B ' Binary mode (added to the other mode) ' + ' Read/write mode (added to mode) where ' + ' can be added in any one mode Later, which means that readable writable ' B ' is used to change different file processing methods, b means binary, video, image, etc. information is a binary file that can be read with the ' RB ' mode, which reads the file in binary form.

8 ex17

From sys import ARGV
From Os.path Import exists

Script, from_file, to_file = argv

Print (' Copy from%s to%s '% (From_file, to_file)

Input=open (From_file)
Indata=input.read ()

Print (' The input file is%d bytes long '%len (indata))

Print (' Does the output ile exist?%r '%exists (to_file))
Print (' Ready,hit return to Continue,ctrl-c to abort. ')
Input ()

Output=open (To_file, ' W ')
Output.write (Indata)

Print (' All right! ')

Output.close ()
Input.close ()

######### #不知道哪里出错了, hint ' typeerror ' _io.textiowrapper ' object is not callable '