Booleans Add Up
| Posted: | 2007-05-31 17:20 |
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| Tags: | Python |
This result surprised me today. If you add True to True in Python you get an integer 2 instead of a TypeError being raised. This is slightly unexpected but presumably there for backwards compatibility?
Python 2.4.4 (#2, Apr 5 2007, 20:11:18) [GCC 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> True True >>> False False >>> True+False 1 >>> False+False 0 >>> True+True 2
Comments
Paddy3118
| Posted: | 2007-05-31 21:11 |
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The two boolean constants True and False are defined to have the integer values 1 and 0 when used in a numerical context.
Many processors have represented false as the value zero. Many programming languages picked up on this and used integer zero as false and any other integer value as representing true. C does this and Pythons ideas of true and false are rooted in that, but with nobs on: http://docs.python.org/lib/truth.html, http://docs.python.org/lib/node34.html .
Paddy.
| URL: | http://paddy3118.blogspot.com |
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