Your First Python Program
=========================
Traditionally, the first program written in a new language is called
``Hello, World!`` because all it does is display the words, *Hello, World!* on
the screen. In Python, the source code looks like this.
.. sourcecode:: Python
print("Hello, World!")
.. index:: ! print function
This is an example of using the **print function**, which doesn’t actually
print anything on paper. It displays a value on the screen. In this case, the
result is the phrase:
::
Hello, World!
.. _hello-world:
Try It!
-------
Type ``print("Hello, World!")`` into the code editor below, then click the
green *Run* button.
.. admonition:: Warning
Do NOT just copy/paste the code. You will learn best by typing, trying,
changing, and fixing.
.. raw:: html
The quotation marks inside the parentheses () mark the beginning and end of the
value to display. They don’t appear in the result.
Some people judge the quality of a programming language by the simplicity of
the ``Hello, World!`` program. By this standard, Python does very well.
.. admonition:: Note
If you typed correctly, you saw the output ``Hello, World!``. If you left out
or mistyped any characters, then you either saw a misspelled output or an
error message. Do not worry if you make mistakes! These experiences still
teach you something. Fix any errors and try again.
Now Play
--------
Once you print ``Hello, World!`` successfully, go back and play around with the
code. Make a change, click *Run*, and see what happens. Try to:
#. Change the message printed.
#. Figure out what the parentheses do. Will the code work without them?
#. Remove one or both quotation marks. Do we need to include both *opening* and
*closing* marks?
#. Is there a difference between using a single or a double quote (``'`` vs.
``"``)?
#. Print multiple messages one after the other.
#. Print two messages on the same line.
#. Print a number. (Bonus: Print two numbers added together).
#. Print a message that contains quote marks, such as ``You're`` or ``I can
print, "Hello, World!"``.
#. Other. You choose!
Spend a few minutes trying these changes. Do not worry if you miss some of the
targets. Learning comes through experience, and you WILL learn all the details
behind ``print`` soon.
Once you finish practicing (and hopefully making some mistakes), you will have
a pretty good idea of how the ``print`` function in Python works.
.. admonition:: Try It
On paper (or in a document on your computer), write one or two sentences about
``print``. You should provide more detail than, “It prints things.”
Check Your Understanding
-------------------------
.. admonition:: Question
The print function:
.. raw:: html
sends information to be printed on paper.
displays a value on the screen.
tells the computer to put the information in print, rather than cursive, font.
tells the computer to speak the information.
.. Answer = b.
.. admonition:: Question
Which of the following correctly prints ``Coding Rocks``? Select ALL that
apply.
.. raw:: html