Understanding raw_input function in Python

Question

I have the following code:

age = raw_input("How old are you? ")
height = raw_input("How tall are you? ")
weight = raw_input("How much do you weigh? ")
print " So, you're %r old, %r tall and %r heavy." %(age, height, weight)

Ok so the raw_input function can standard output without a trailing newline. The function then reads a line from input, converts it to a string (stripping a trailing newline), and returns that.

What I don't understand is why every prompt message is presented on a new line since raw_input only returns a string. It doesn't add a newline and I don't have any \n in the code.

When you enter the input, do you press the Enter key when you are done? — murgatroid99
– murgatroid99, Commented Oct 18, 2011 at 18:39
@murgatroid99: True, although one might think, as Enter "sends" the input to the application, that it is not part of the input anymore... but well... it is. — Felix Kling
– Felix Kling, Commented Oct 18, 2011 at 18:44
Is what you are looking for is to have all the prompts on the same line? raw_input can't do that. You could try curses or msvcrt on windows. — jgritty
– jgritty, Commented Oct 18, 2011 at 18:49
@murgatroid99 Like Felix Kling said, I thought Enter is not part of the input. Seems like I was wrong. Thanks for pointing this out to me. — 0101amt
– 0101amt, Commented Oct 18, 2011 at 18:50

Vasiliy Sharapov · Accepted Answer · 2011-10-18 18:51:16Z

4

When you type a response to the raw_input() you finish by entering a newline. Since each character you enter is also displayed as you type, the newline shows up as well.

If you modified the python builtins and changed raw_input you could get it to terminate on '.' instead of '\n'. An interaction might look like: How old are you? 12.How tall are you? 12.How much do you weigh? 12. So you're ...

answered Oct 18, 2011 at 18:51

Vasiliy Sharapov

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jgritty · Accepted Answer · 2011-10-18 19:00:11Z

1

Here is a way to do it in windows, using msvcrt. You could do a similar thing on Mac or unix using curses library.

import msvcrt
import string

print("How old are you? "),
age = ''
key = ''
while key != '\r':
    key = msvcrt.getch()
    age += key
print("How tall are you? "),
key = ''
height = ''
while key != '\r':
    key = msvcrt.getch()
    height += key
print("How much do you weigh? "),
key = ''
weight = ''
while key != '\r':
    key = msvcrt.getch()
    weight += key
print "\n So, you're %r old, %r tall and %r heavy." %(string.strip(age), string.strip(height), string.strip(weight))

Sample output looks like this:

How old are you?  How tall are you?  How much do you weigh?
 So, you're '37' old, "6'" tall and '200' heavy.

answered Oct 18, 2011 at 19:00

jgritty

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1 Comment

jgritty Over a year ago

You could have it echo back the characters to the screen as well, but notice it's not outputting the user's input until the end.

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