print call in python 3.4

Question

Hi I'm teaching myself python, have downloaded 3.4 and am working through Think Python. The problem i'm having is printing a grid. I won't put the whole code up but the bit that is a problem.

def do_twice(f):  
    f()  
    f()

def print_beam():   
    print("+ - - - - ", )

def print_beams():  
    do_twice(print_beam)
    print("+")

now this when called is supposed to print a beam like this + - - - - + - - - - +

However, the actual output is
+ - - - -
+ - - - -
+

I've spent a good two hours on this but the version of python i'm using is different from the book I'm working on. Could anyone help me out of this log jam?

What version are you using? If you aren't sure, try import sys; print(sys.version) — Kevin
– Kevin, Commented Mar 4, 2016 at 19:52
You're reading a Python 2 tutorial and running it on Python 3. That's the problem. — Ashwini Chaudhary
– Ashwini Chaudhary, Commented Mar 4, 2016 at 19:54
If your book suggested putting a comma at the end of a print statement in order to suppress a newline, then it's almost certainly written for 2.7 or lower. I assume that's why you've got a stray comma in your print_beam function? — Kevin
– Kevin, Commented Mar 4, 2016 at 19:56

Gareth · Accepted Answer · 2016-03-04 19:55:18Z

5

The problem is that, by default, the print function creates a new line at the end of its output. Here's an easy fix.

def do_twice(f):  
    f()  
    f()

def print_beam():   
    print("+ - - - - ", end='') #Don't create a new line.

def print_beams():  
    do_twice(print_beam)
    print("+")

answered Mar 4, 2016 at 19:55

Gareth

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2 Comments

Mark Nolan Over a year ago

Thanks for your help Gareth, that has fixed it immediately. So glad I came here instead of banging my head for another 2 hours. Thanks so much!

Gareth Over a year ago

@MarkNolan Don't forget to mark this as the answer for others passing by!

Myles Offord · Accepted Answer · 2016-03-04 19:56:44Z

1

With python 3 to prevent newline characters being printed set end="" like so:

print("+ - - - -", end="")

You can read the documentation on this here

answered Mar 4, 2016 at 19:56

Myles Offord

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Comments

Mackin · Accepted Answer · 2020-03-23 12:51:33Z

0

print statements with argument (end), lets you continue on the next line. i used python 3.8 version

def print_beam():
    print('+',end=' ')
    print('-','-','-','-', end=' ')
    print('+', end=' ')
    print('-', '-', '-', '-', end=' ')
    print('+')

def print_column():
    print('|',end=' ')
    print(' ',' ',' ',' ', end=' ')
    print('|', end=' ')
    print(' ', ' ', ' ', ' ', end=' ')
    print('|')

answered Mar 23, 2020 at 12:51

Mackin

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1 Comment

David Baak Over a year ago

This does not answer his question

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