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How to do Input in Python?

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Re: How to do Input in Python?

#11

Dec 22nd, 2008

print 'What is you name?'
Raw_input()

Last edited by Flare; Dec 22nd, 2008 at 3:04 pm.

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Re: How to do Input in Python?

#12

Dec 23rd, 2008

Or you can one-line it:
print raw_input('What is your name? ')

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Re: How to do Input in Python?

#13

Dec 23rd, 2008

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Originally Posted by Flare

print 'What is you name?'
Raw_input()

If you run it you will get error
NameError: name 'Raw_input' is not defined

That is because your version of raw_input() is Raw_input()

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Re: How to do Input in Python?

#14

May 31st, 2009

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Originally Posted by reezin14

From what I understand you would use, input as to prompt the user to input a number and raw_input to prompt a string

No. You would use raw_input() for both normally, but you add int() if what you want is an int, or float() if you want a floating point number.

 Help with Code Tags 
 Python Syntax (Toggle Plain Text) 
s = raw_input( "Type a string: " ).rstrip( '\n' )
n = int( raw_input( "Type an int: " ).rstrip( '\n' ) )
f = float( raw_input( "Type a float: " ).rstrip( '\n' ) )
s = raw_input( "Type a string: " ).rstrip( '\n' )
n = int( raw_input( "Type an int: " ).rstrip( '\n' ) )
f = float( raw_input( "Type a float: " ).rstrip( '\n' ) )

The "rstrip('\n')" takes the newline character off the end of what they type.

The only time you would use input() is if you want the user to be able to type any Python code they want, so they have the power to type in a complicated expression like "sin( pi/7 )" ... or erase all your files ... as part of their answer.

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Re: How to do Input in Python?

#15

May 31st, 2009

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Originally Posted by tharippala

Looks like a funny issue, I couldn't re - produce it. But Ican suggest you the solution.

try this,

print "Why "+ test.strip() +" there a line break all the time?"

It has to work out, strip will help you to remove the newline charecter from test

Well, strip() will take any whitespace characters off the beginning or end of the string. If you really only want to take the newline off the end, do this:

 Help with Code Tags 
 Python Syntax (Toggle Plain Text) 
print "Now " + test.rstrip( '\n' ) + " doesn't have a break in it."
print "Now " + test.rstrip( '\n' ) + " doesn't have a break in it."

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Re: How to do Input in Python?

#16

May 31st, 2009

stdout vs. stderr

One more issue with input() and raw_input() is that they print the prompt on the standard output! In Unix I almost always want prompts to go to standard error instead. But doing this is tricky. If you do this:

 Help with Code Tags 
 Python Syntax (Toggle Plain Text) 
from sys import stderr
print >>stderr, "Type a string: ",
s = raw_input().rstrip( '\n' )
print >>stderr, "You typed:", s
from sys import stderr
print >>stderr, "Type a string: ",
s = raw_input().rstrip( '\n' )
print >>stderr, "You typed:", s

Then you get something like this:

Help with Code Tags

Python Syntax (Toggle Plain Text)

Type a string: hello
 You typed: hello

An extra space comes out on the next print to stderr because of the comma when you printed the prompt. The only correct way to do it I know is this:

 Help with Code Tags 
 Python Syntax (Toggle Plain Text) 
from sys import stderr
stderr.write( "Type a string: " )
stderr.flush()
s = raw_input().rstrip( '\n' )
print >>stderr, "You typed: ", s
from sys import stderr
stderr.write( "Type a string: " )
stderr.flush()
s = raw_input().rstrip( '\n' )
print >>stderr, "You typed: ", s

(Hey, emacs control characters work in this editor, kewl!)

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Re: How to do Input in Python?

#17

May 31st, 2009

Forgot, I wanted to say: rstrip( '\n' ) is what you typically want to do to lines you read from a file. It won't take indentation off the lines! E.g.,

 Help with Code Tags 
 Python Syntax (Toggle Plain Text) 
for line in open( filename ):
   line = line.rstrip( '\n' )
   # blah blah...
for line in open( filename ):
   line = line.rstrip( '\n' )
   # blah blah...

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Re: How to do Input in Python?

#18

Jun 23rd, 2009

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Originally Posted by Rete

I have another problem with pythons Input, and I was wondering if someone could help me. Whenever I get any input from the user, python keeps printing out on a new line.
So for example:

test = raw_input ("Input word")
print "Why "+ test +" there a line break all the time?"

So if my inputted word was "is", the program would output this:

Why is
there a line break all the time?

Im guessing its because python is including the ENTER key used whenever I'm finished with input, but I'm not sure how to stop that. Any help would be appreciated. :D

There's a faster fix to this, just use this:

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
test = raw_input ("Input word").strip()
print "Why "+ test +" there a line break all the time?"
test = raw_input ("Input word").strip()
print "Why "+ test +" there a line break all the time?"

That beats having to make sure you enter the ".strip()" every time that you want to print the var like this:

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
test = raw_input("Input word")
print "Why" + test.strip() + " there a line break all the time?"
test = raw_input("Input word")
print "Why" + test.strip() + " there a line break all the time?"

You could also make it easier by doing this:

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
test = raw_input("Input word").strip()
print "Why %s there a line break all the time?" % test
test = raw_input("Input word").strip()
print "Why %s there a line break all the time?" % test

Or to use the first example:

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
var = raw_input("Type something: ").strip()
print "You typed %s" % var
var = raw_input("Type something: ").strip()
print "You typed %s" % var

Or, maybe you have multiple vars:

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
name = raw_input("Enter your name: ").strip()
email = raw_input("Enter your email: ").strip()
print "Hello %s!\nThe email address we have for you is '%s'." % (name, email)
name = raw_input("Enter your name: ").strip()
email = raw_input("Enter your email: ").strip()
print "Hello %s!\nThe email address we have for you is '%s'." % (name, email)

Or, better yet, make the prompt a function if you're asking for a lot of information:

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
import sys
def prompt():
    response = sys.stdin.readline().strip()
    return response
 
fields = [ "Name: ", "Email: ", "Phone: " ]
 
answers = []
for field in fields:
    print field,
    v = prompt()
    answers += [v]
 
print """Hello %s!
Your Email is: %s
Your Phone is: %s""" % ( answers[0], answers[1], answers[2] )
import sys
def prompt():
    response = sys.stdin.readline().strip()
    return response

fields = [ "Name: ", "Email: ", "Phone: " ]

answers = []
for field in fields:
    print field,
    v = prompt()
    answers += [v]

print """Hello %s!
Your Email is: %s
Your Phone is: %s""" % ( answers[0], answers[1], answers[2] )

With the above process, the user will see:

Name: Joe
Email: joe@domain.com
Phone: 555-1234

Hi Joe!
Your Email is: joe@domain.com
Your Phone is: 555-1234

Hope that helps!

Last edited by Hummdis; Jun 23rd, 2009 at 3:54 pm. Reason: Gramatical changes.