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Today, I would like to share with you Python's print output function and input input function how to use the relevant knowledge points, detailed content, clear logic, I believe that most people still know too much about this knowledge, so share this article for your reference, I hope you can get something after reading this article, let's take a look at it.

1. Get command line parameters

When you execute a Python script, you can pass parameters to the script from the command line, receive them within the script, and separate each parameter.

1.sys.argv

The first step of the usage:

Import sys

The second step of the method is:

Temp=sys.argv [1]

[explain here, index 0 in the sys.argv sequence corresponds to the Python script name, and the rest are the variables passed in] the following code will print the Python file name and the parameters you pass in (error will be reported if you do not pass parameters)

Import sysn1=sys.argv [0] n2=sys.argv [1] print (N1 Magnum type (N1)) print (N2 recorder type (N2)) 2.argparse

This module is a Python standard module that parses command-line arguments and generates help information.

The first step (guide package):

Import argparse

Step 2 (create an ArgumentParser object):

Margs=argparse.ArgumentParser ()

Step 3 (increase the command line parameter information to be parsed):

Margs.add_argument (parameter name, default value, type, prompt statement)

Step 4 (generate parameter list):

Args=margs.parse_args ()

Second, the most commonly used input and output 1.print function [output]

① print function prototype

Explain the parameter list:

* args represents non-fixed parameters

The space between sep representatives defaults to a space

End stands for adding line breaks at the end of the output

File represents whether to redirect the output stream to a file. Is a file descriptor

The pass at the end represents a placeholder because python is a language with strict syntax formatting requirements

Function, loop language can not be left blank generally use pass to occupy the position.

Def print (self, * args, sep='', end='\ n é, file=None): # known special case of print "" print (value,..., sep='', end='\ n, file=sys.stdout, flush=False) Prints the values to a stream, or to sys.stdout by default. Optional keyword arguments: file: a file-like object (stream); defaults to the current sys.stdout. Sep: string inserted between values, default a space. End: string appended after the last value, default a newline. Flush: whether to forcibly flush the stream. " Pass

② uses the print function

Print function can print numbers, operation addition and subtraction

You can output a string (the string must be enclosed in double or single quotation marks, otherwise the interpreter will not understand what is entered)

Print can direct the output directly to the file, and the open function opens the file.

There is no need to import header files to create python scripts, and third-party packages are import only when a library is used.

# 1. Output digital print (888) # 2. Output expression print (1x3) # output string print ('Hello World') print (' Hello World', "Hello Kity") # print function outputs the content directly into the file # opens the file test.txt to get the file descriptor F and then outputs the file. F = open ('test.txt', "a +") print (' Hello File', file=F) F.close () 2.input function [input]

① input function prototype

The input function is a common input function in Python, which can read the data input in the black window.

Def input (* args, * * kwargs): # real signature unknown "" Read a string from standard input. The trailing newline is stripped. The prompt string, if given, is printed to standard output without a trailing newline before reading input. If the user hits EOF (* nix: Ctrl-D, Windows: Ctrl-Z+Return), raise EOFError. On * nix systems, readline is used if available. "" Pass

② uses the input function

# input function input# input function box is filled with informative statements # input is the string type q=input ('Please enter your name') print (type (Q)) print ("my name is:", Q) # input (can type conversion directly) q=int (input ("Please enter your data:") print (type (Q)) 3, input and output under sys package

In terms of name, this package is about the system, if print and input can't meet your needs.

Take a look at sys.stdin and sys.stdout. Print and input are encapsulated on the basis of the latter.

1.sys.stdin

For more standard input than input, you can use his method readline () to read one line at a time

The read line contains all the special characters and subsequent newlines, if you do not want to read the newline into the

To add strip () after readline.

The code is as follows:

# first, guide the package import sys# to read a line directly, including the newline character str1=sys.stdin.readline () # read a line without the final newline character str2=sys.stdin.readline (). Strip () 2.sys.stdout

This is a more official output than the print function, because print is encapsulated on its basis. For Python, sys.stdout.write ("Hello World" + "\ n") has the same effect as print ("Hello World"). Sys.stdout also supports redirection of output. The method of operation is to directly put the standard output

The object points to the file descriptor. If you want to restore standard output, you only need to point the input and output object to the standard input and output object again.

The code is as follows:

Import sys# creates a file descriptor f1=open ("log.txt", "w") # redirects standard output to the file log.txt sys.stdout=f1# write information sys.stdout.write ("Hello") # restore redirect sys.stdout=sys.__stdout__ IV. Command line script redirection

In life, we may have such a need, that is, to test the code we have written. When testing, it is very troublesome if we input a large amount of data every time, and there will be a need to print logs. If the log is printed to the screen each time, it may be refreshed. So our input and output redirection comes. Input and output redirection is generally to print the data on the screen to a file, or to read the data from the screen instead of reading from the file.

1. Redirect standard output

Send the execution result of the script directly to the file and save it permanently.

The syntax is: python file. Py > save file eg: python test.py > output.txt

The code is as follows:

Import sysnum=int (input ()) # num=int (sys.argv [1]) flag=Truefor i in range (1 and temp%2==0 and temp//2 10): for j in range (0 and temp%2==0 and temp//2 10): temp=num-2*i-2*j if temp=0: print (i*10000+j*1000+temp*100+j*10+i) flag=Falsefor i in range (1 line 10): for j in range (0 and temp%2==0 and temp//2 10):

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