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<pre>
print "I'm a happy camper"
</pre>▼
 
or we can <b>escape</b> the quote with a backslash:
 
<pre>▼
print 'I\'m a happy camper'
print 'Ada Lovelace is often called the world\'s first programmer.'
print "Computer scientist Grace Hopper popularized the term \"debugging\"."
</pre>
 
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c = "fox jumps over the lazy dog"
print "The " + a * 3 + " " + b * 3 + " " + c
</pre>▼
 
3.
<pre>▼
print 2.0 * 123 + str(2.0) * 123
</pre>
 
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<b>Step 1: write a function signature</b>
 
A <b>function signature</b> tells you how the function will be called. It starts with the keyword <code>def</code>, which tells Python that you are defining a function. Then comes a space, the name of your function, an open parenthesis, the comma-separated input <b>parametersarguments</b> for your function, a close parenthesis, and a colon. Here's what a function signature looks like for a function that takes no arguments:
 
<code>def myFunction():</code>
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<code>def myFunction(myList, myInteger):</code>
 
ParametersArguments should have names that usefully describe what they are used for in the function.
 
We've used the words <b>parameters</b> and <b>arguments</b> seemingly interchangeably to reference the input to functions. The distinction isn't really important right now, but if you're curious: in function signatures the input is called parameters, and when you are calling the function the input is called arguments.
 
<b>Step 2: do useful work inside the function</b>
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Underneath the function signature you do your useful work. Everything inside the function is indented, just like with if/else blocks, so Python knows that it is a part of the function.
 
You can use the variables passed into the function as parametersarguments, just like you can use variables once you define them outside of functions.
 
<pre>
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Functions don't have to return anything, if you don't want them to. They usually return something because we usually want to be able to assign variables to their output.
 
====What is the difference between <code>print</code> and <code>return</code>?====
 
Think for a moment about the differences between <code>print</code> and <code>return</code>:
 
* <code>print</code> prints output to the screen so your eyes can see it.
 
* <code>return</code> is used to hand off a value from inside a function to a variable outside the function.
 
For example:
 
▲<pre>
def add(x, y):
print x + y
▲</pre>
 
will print <code>x + y</code> to the screen so your eyes can see it.
 
▲<pre>
def add(x, y):
return x + y
▲</pre>
 
will hand off <code>x + y</code> from inside the function to outside the function. This allows you to do something like:
 
<pre>
result = add(5, 6)
print result
</pre>
 
Does that make sense? If not, talk about it with a neighbor or staff member.
 
==End of Part 2==
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[[BostonMontreal Python Workshop 7/Friday|&laquo; Back to the Friday Workshop page]]
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