Boston Python Workshop 4/ColorWall handout: Difference between revisions

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Thanks for saihnrg. Always good to find a real expert.
====Indentation reminder====

In Python, indentation matters. Everything is indented by a multiple
of some number of spaces, often 4.

In <code>if</code> statements, you indent everything you want to be run if the if
conditional is <code>True</code>. For example:

<pre>
>>> James = 35
>>> Alice = 30
>>> if James > Alice:
... print "James is older than Alice."
...
James is older than Alice.
>>></pre>

Because James really is older than Alice, the <code>if</code> conditional is <code>True</code>,
so Python does execute the code indented under the if line. In this
case we print "James is older than Alice."

<pre>
>>> James = 35
>>> Alice = 30
>>> if James < Alice:
... print "James is younger than Alice."
...
>>></pre>

Because James is not older than Alice, the <code>if</code> conditional is <code>False</code>, so
Python does not execute the code indented under the if line.

In for loops, you indent everything you want to be run each loop For
example:

<pre>
>>> names = ["Jessica", "Adam", "Liz"]
>>> for name in names:
... print "Hello", name
...
Hello Jessica
Hello Adam
Hello Liz</pre>

The <code>print</code> line is indented 4 spaces under the <code>for</code>. That's how
Python knows to execute the print line for every name in names.

Latest revision as of 21:29, 15 January 2012

Thanks for saihnrg. Always good to find a real expert.

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