Take input from stdin in Python

In this article, we will see How to Read from stdin in Python. 

There are a number of ways in which we can take input from stdin in Python. 

• sys.stdin
• input()
• fileinput.input()

Method 1: Read Input From stdin in Python using sys.stdin

The sys module in python helps us to access the variables maintained by the interpreter. It also provides functions to interact with the interpreter. To use sys in Python, we firstly import sys

Using sys.stdin: sys.stdin can be used to get input from the command line directly. It used is for standard input. It internally calls the input() method. It, also, automatically adds ‘\n’ after each sentence. let see a sys stdin python example:

Python3

import sys

for line in sys.stdin:
    if 'q' == line.rstrip():
        break
    print(f'Input : {line}')

print("Exit")

Output

Method 2:Read Input From stdin in Python using input()

The input() can be used to take input from the user while executing the program and also in the middle of the execution.

Python3

# this accepts the user's input
# and stores in inp
inp = input("Type anything")

# prints inp
print(inp)

Output:

Method 3: Read Input From stdin in Python using fileinput.input()

Using fileinput.input(): If we want to read more than one file at a time, we use fileinput.input() . There are two ways to use fileinput.input(). To use this method, first, we need to import fileinput.

Example 1:

Here, we pass the name of the files as a tuple in the “files” argument. Then we loop over each file to read it.

Python3

import fileinput

with fileinput.input(files=('sample.txt', 'no.txt')) as f:
    for line in f:
        print(line)

Output: 

Example 2:

Here, we pass the file name a sys argument in the command line. 

Python3

import fileinput

for f in fileinput.input():
    print(f)

Output: