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POIs False == 0 and True == 1 in Python an implementation detail or is it guaranteed by the language?
 

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  1. POIs False == 0 and True == 1 in Python an implementation detail or is it guaranteed by the language?
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    <p>Is it guaranteed that <code>False == 0</code> and <code>True == 1</code>, in Python (assuming that they are not reassigned by the user)? For instance, is it in any way guaranteed that the following code will always produce the same results, whatever the version of Python (both existing and, likely, future ones)?</p> <pre><code>0 == False # True 1 == True # True ['zero', 'one'][False] # is 'zero' </code></pre> <p>Any reference to the official documentation would be much appreciated!</p> <p><strong>Edit</strong>: As noted in many answers, <code>bool</code> inherits from <code>int</code>. The question can therefore be recast as: "Does the documentation officially say that programmers can rely on booleans inheriting from integers, <em>with the values <code>0</code> and <code>1</code></em>?". This question is relevant for writing robust code that won't fail because of implementation details!</p>
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    1. COIf you suspect it to be a detail, why not avoid the detail? Why ask a question like this? It's trivial to avoid depending on this kind of functionality. For your example, use a dictionary instead of a list. What problem are you having? Why ask this?
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    2. CO@S.Lott: There are many reasons to ask the question above. Thus, there are instances where relying on booleans being integer makes your code simpler: do you have to change it? Or, you might spot places in a code written by someone else that relies on booleans being integers: do you interrupt what you are modifying in the code in order to "fix" existing code, or can you rest assured that the current coding is sound? There is a plethora of other examples. More generally, it is good to know the rules of the game, so that you can play it well and program in a sound way.
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    3. CO@EOL: can you provide an example of "relying on booleans being integer makes your code simpler"? I can't imagine such a thing. " do you interrupt what you are modifying in the code in order to "fix" existing code, or can you rest assured that the current coding is sound?" The question seems technical, not "how do I cope?" The rules are simple: **don't depend on implementation details**. So why ask about an implementation detail?
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