How do you read from stdin?

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I'm trying to do some of the code golf challenges, but they all require the input to be taken from stdin. How do I get that in Python?

You could use the fileinput module:

import fileinput

for line in fileinput.input():
    pass

fileinput will loop through all the lines in the input specified as file names given in command-line arguments, or the standard input if no arguments are provided.

Note: line will contain a trailing newline; to remove it use line.rstrip()

How to Read from stdin in Python, There are three ways to read data from stdin in Python. sys.stdin input() built-in function fileinput.input() function 1. Using sys.stdin to read from. sys.stdin is a file-like object on which we can call functions read() or readlines(), for reading everything or read everything and split by newline automatically. Example: from sys import stdin input = stdin . read ( 1 ) user_input = stdin . readline ( ) amount = int ( user_input ) print ( "input = {}" . format ( input ) ) print ( "user_input = {}" . format ( user_input ) ) print ( "amount = {}" . format ( amount ) )

Using STDIN for inputs and STDOUT for outputs – HackerRank , Using STDIN for inputs and STDOUT for outputs. STDIN. a= Console. Readline(); b = Console. Readline(); scanf("%d,%d", &num1, &num2) STDOUT - This is the standard stream to write or print the output from your code. For example, for the above-mentioned coding question, you need to write the output from your program. STDIN. This is the standard stream to provide or read input values to a program. For example, consider a HackerRank sample question to read two integers, say a and b, and return their sum as the output. If coding in C#, you must use Console. ReadLine() to read input values from Test Cases into the variables a and b. a= Console.Readline();

import sys

for line in sys.stdin:
    print(line)

Note that this will include a newline character at the end. To remove the newline at the end, use line.rstrip() as @brittohalloran said.

Java Stdin and Stdout I, Most HackerRank challenges require you to read input from stdin (standard input​) and write output to stdout (standard output). One popular way to read input  I'm trying to read from stdin and output the data, things work, EXCEPT that it's not outputting the new incoming data.I'm not quite sure where is the issue. I'm guessing it has something to do when determining the stdin size.

Python also has built-in functions input() and raw_input(). See the Python documentation under Built-in Functions.

For example,

name = raw_input("Enter your name: ")   # Python 2.x

or

name = input("Enter your name: ")   # Python 3

C - Input and Output, The scanf() and printf() Functions​​ function reads the input from the standard input stream stdin and scans that input according to the format provided. The int printf(const char *format, ) function writes the output to the standard output stream stdout and produces the output according to the format provided. Stack Overflow Public questions and answers; Teams Private questions and answers for your team; Enterprise Private self-hosted questions and answers for your enterprise; Jobs Programming and related technical career opportunities

Here's from Learning Python:

import sys
data = sys.stdin.readlines()
print "Counted", len(data), "lines."

On Unix, you could test it by doing something like:

% cat countlines.py | python countlines.py 
Counted 3 lines.

On Windows or DOS, you'd do:

C:\> type countlines.py | python countlines.py 
Counted 3 lines.

StdIn, Reading tokens from standard input and converting to numbers and strings. You can use the following methods to read numbers, strings, and booleans from  If you close(1), the stdin file will be closed. And then, if you open another file, the stdin will be point to the new file. All input APIs(scanf, get, ) without FD are read data from input file, and output APIs without FD are put the value into stdout. So, if you close(1), and open a new file with return value is 1, the printf will put

Hour 5, Additionally, in C, there are three file streams that are pre-opened for you: stdin–​The standard input for reading. stdout–The standard output for writing. stderr–The​  Now you can certainly set up QTimer and set up a handler for the timeout() signal to read from stdin as well. The method of implementing is entirely up to you. And for the second method you can take a look at QT's timer class documentation for an example on how to do this. One thing to remember would be to actually restart the timer once your processing is completed.

Why isn't it possible to read from `stdin` with `read` when piping a , You did read from stdin with read , but what you read was the next line of standard input - namely echo "Hello $NAME" . After reading that line,  According to me sys.stdin.read() method accepts a line as the input from the user until a special character like Enter Key and followed by Ctrl + D and then stores the input as the string. Control + D works as the stop signal.

Command-line app to read from stdin and write to stdout., Most good Unix/Linux apps accept their input from the system's standard input device and write Duration: 2:50 Posted: Nov 28, 2017 To read from stdin you can use the below-mentioned code:-import sys . for line in sys.stdin: print line.

Comments
  • The question is about reading from the process std in stream. Like cin in c
  • @BorislavStoilov And this answer does correctly answer the question: "or the standard input if no arguments are provided".
  • line.rstrip('\n'), otherwise it will drop all the whitespaces
  • using this method, how do we know when the input stream ends? I want to add comma after every line excepts for the last line.
  • I receive: TypeError: 'FileWrapper' object is not iterable.
  • @avp this will not correctly deal with \r\n line endings
  • This reads a single line, which isn't really what the OP asked about. I interpret the question as "how do I read a bunch of lines from an open file handle until EOF?"
  • The OP isn't asking to read input from a keyboard, He is asking to read from stdin which in a contest situation is usually provided to the contestants.
  • this is what i needed, google brought me here. interestingly i managed to code rfid tags, datetime, databases, but never bothered to read input from the user lol
  • Here's a more memory efficient (and maybe faster) way to count lines in Python: print(sum(chunk.count('\n') for chunk in iter(partial(sys.stdin.read, 1 << 15), ''))). see wc-l.py
  • The use of cat here is redundant. The correct invocation for Unix systems is python countlines.py < countlines.py.
  • "Learning Python" is wrong in directing users to use readlines(). File objects are intended to be iterated over without materializing all of the data in memory.