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06/01/12 20:30
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 		 #187601 - Very Important
Responding to: ???'s previous message
Andy Peters said:
Justin Fontes said:
Per said:
An expression with multiple || will (and must) end evaluation on first true.
An expression with multiple && will (and must) end evaluation on first false.


Completely true. This is called Short-circuit evaluation and details can be found here:

http://en.wikipedia.org/wiki/Shor...evaluation

Pretty good for being able to point to this out, Per.


Excellent, thanks for the clear explanation.

-a


Yes, and this behavior of the C language can and sometimes is used to advantage in certain types of expressions. When you are studying code from someone else or doing design review type work lack of knowledge about how the language handles multi term expressions can be a killer.

Michael Karas

List of 33 messages in thread
TopicAuthorDate
Where can one learn Intermediate C techniques for 8051            01/01/70 00:00      
   on the right track            01/01/70 00:00      
      one more thing            01/01/70 00:00      
         Not uncommon bid bad coding standards to comply with            01/01/70 00:00      
         Not afraid of globals, but...            01/01/70 00:00      
   More keil optimizer interesting tidbits            01/01/70 00:00      
      optimization            01/01/70 00:00      
      nothing gained, nothing lost            01/01/70 00:00      
         I don't            01/01/70 00:00      
            you can do both            01/01/70 00:00      
               That is not helping the compiler            01/01/70 00:00      
                  exact same            01/01/70 00:00      
                     Technically, they are not the same            01/01/70 00:00      
                        Hmmm...            01/01/70 00:00      
                        C don't do full evaluation of logical expressions            01/01/70 00:00      
                           In discrete mathematics proving one is not a proof            01/01/70 00:00      
                              Lazy evaluation demanded            01/01/70 00:00      
                                 I have learned something new because of this            01/01/70 00:00      
                                    me too            01/01/70 00:00      
                                       Very Important            01/01/70 00:00      
                              Breaks.            01/01/70 00:00      
                                 Compile the code            01/01/70 00:00      
                                    To be more exact            01/01/70 00:00      
                                       Stop It!!            01/01/70 00:00      
                                          That is exactly what I intended            01/01/70 00:00      
                                             Switch Break.            01/01/70 00:00      
               obfusciating code to help the compiler is a VERY bad idea            01/01/70 00:00      
                  the source of this            01/01/70 00:00      
   Where can one learn Intermediate C techniques for 8051            01/01/70 00:00      
   Getting the least out of your compiler            01/01/70 00:00      
      Maybe IAR should follow their own advice?            01/01/70 00:00      
         provided the case ...            01/01/70 00:00      
            Compilers not knowing the target chip.            01/01/70 00:00      

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