Hello world in Python

Installing Python

Depending on your operating system, you may need to download Python.  Most Linux distributions come with Python as does Mac OS X.  Windows does not ship with Python.  To test if Python is installed, open a command prompt and enter:

python

Hello world in Python (prior version 3):

Writing a "Hello word" program in Python is trivial:

print "Hello world"

In the interactive interpreter, it looks like this:


This Knol also introduces the print command:

The print command

A print command in Python adds a line feed, so with two prints you will get two lines:

print "Hello"
print "world"

Hello
world

This can be avoided by using a period (,) at the end:

print "Hello",
print "world"  

Hello world

Hello world using variables:

>>> h = "Hello"
>>> w = "world"
>>> print h+' '+w
Hello world

Note that the "+" operation concatenates three strings: Hello, a "space" character and "world".

Printing with placeholders

>>> print "%s %s" %(h,w)
Hello world

By using "%s" you don't have to concatenate strings, just use one string and put a placeholder (the %s) where the variable

Python 3

In Python 3, the print statement is transformed into a function, so a basic hello world, is: