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Boston Python workshop 2/Friday tutorial: Difference between revisions
Boston Python workshop 2/Friday tutorial (view source)
Revision as of 23:47, 26 May 2011
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==Booleans==
So far, the code we've written has been <i>unconditional</i>: no choice is getting made, and the code is always run. Python has another data type called a <b>boolean</b> that is helpful for writing code that makes decisions. There are two booleans: <code>True</code> and <code>False</code>:
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type(False)
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You can test if Python objects are equal or unequal:
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0 == 1
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Use <code>==</code> to test for equality. Recall that <code>=</code> is used for <i>assignment</i> (e.g. <code>my_string == "Hello"</code>).
<code>=</code> is assignment, <code>==</code> is comparison.
Use <code>!=</code> to test for inequality:
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"a" != "a"
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"a" != "A"
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<code><</code>, <code><=</code>, <code>></code>, and <code>>=</code> have the same meaning as in math class:
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1 > 0
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2 >= 3
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-1 < 0
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.5 <= 1
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You can check for containment with the <code>in</code> keyword:
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"X" in "Hello"
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Or check for a lack of containment with <code>not in</code>:
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"Elvis" not in "Elvis has left the building"
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