When is calculating or variable-reading faster?

Posted by Andreas Hornig on Stack Overflow See other posts from Stack Overflow or by Andreas Hornig
Published on 2010-03-16T12:22:50Z Indexed on 2010/03/16 12:26 UTC
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to be honest, I don't really know what the "small green men" in my cpu and compiler do, so I sometimes would like to know :).

Currently I would like to know what's faster, so that I can design my code in a more efficient way. So for example I want to calclate something at different points in my sourcecode, when will it be faster to calculate it once and store it in a variable that's read and used for the next points it's needed and when is it faster to calculate it everytime?

I think it's depending on how "complex" and "long" the calculation is and how fast then cache is, where variables are stored, but I don't have any clue what's faster :).

Thanks for any reply to my tiny but important question!


PS: perhaps it's important to know that I code in JAVA, but it's more a genral question.

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